Algebra question

Err..

I wont be able to do it but arent you missing a set of brackets?

just a V here soz

Brassie will solve this as soon as he appears tonight.

Assuming that there should only be one bracket after (D/8), and you haven't therefore missed anything out ...

V = D((K-L)/40) - (U-120-2X)/16R + S/8)

Scrub that. Just noticed the last number is U-126, not U-120.

Arse.

It's not that hard is it? At the huge risk (dare I say certainty :)) of saying that then doing a collosal embarrasing c0ck up and my brain is frazzled..:
X = 120 - R * (S - (V/(D/8))) + ((R/5) * (L - K)) + (U-126)/2
X - 120 - ((R/5) * (L - K)) - (U-126)/2 = - R * (S - (V/(D/8)))
-(X - 120 - ((R/5) * (L - K)) - (U-126)/2) / R = (S - (V/(D/8)))
-S + (-(X - 120 - ((R/5) * (L - K)) - (U-126)/2) / R) = -(V/(D/8))
(-S + (-(X - 120 - ((R/5) * (L - K)) - (U-126)/2) / R)) * (D/8) = -V
-(-S + (-(X - 120 - ((R/5) * (L - K)) - (U-126)/2) / R)) * (D/8) = V

Intersting though. I didn't expect to the equation for Bradly Wiggans "medicine" intake on the chit chat forum, resolved to average tour de france stage Velocity

V = D((K-L)/40 - (U+114-2X)/16R + S/8)

Just noticed the first solution I posted would have been wrong anyway, even if it were 120 rather than 126. In that case, it should be:
V = D((K-L)/40 - (U+120-2X)/16R + S/8)

Thanks very much to JC & sfb. I'll shove the numbers in & check either tonight or tomorrow & report back.
I'd have thought some would recognize the equation format as a horse speed ratings calculation. The 126 is 9 stone in pounds and the 8 is the 8 furlongs in a mile. There are a number of ways to do this, but I'm aiming to re-calculate standard times from speed ratings. I'm attempting to do every course & distance combination  in a single calculation in a database. I make that 571 C&D combinations for UK & Ire.

I can't be fussed doing it but yes plug in some numbers and see if the result is correct both ways. Obviously my answer could be improved, even if correct, to be a little neater! (no double - etc).

I've always used 10-0 on the Flat and 12-0 over jumps as a basis for estimating standard times. Perhaps I might have guessed what you were up to had the number been 140 or 168 instead of 126.

Well, I wouldn't have, to be honest.

When I did keep speed figures, from about 1985 to 2009, my standard times came from relentlessly fiddling with the numbers until I got figures which simply worked. I found that the only way of dealing with elastic running rails and the fact that so many race distances were not as advertised (e.g. Wincanton's notorious 2m hurdle track) was to make estimates on the basis of going back through years of results to see what looked right.

Funnily enough, it was when they began remeasuring everything from scratch and publishing rail movements that I gave it up. For one thing, when they began moving the starts, they made the whole history of horse racing redundant overnight from a time perspective. And besides, with all the new measurements there on a plate, the problem had been reduced to one of algebra. How was it going to give me an edge, if there was no scope for judgement, experience and decades of "feel" for what was correct?

(The reason I estimated standard times to 10-0 on the Flat was in order to overlap with the weights carried in amateur riders' races; otherwise I found that the amateurs' races always ended up with the fastest relative time on the card; I know that this indicated that there must be a problem with my pounds per second scale, but I was buggered if I could work out what it was; using 10-0 as a basis seemed to solve the problem.)

R = 5.5
S = 100.7
V = 58.1
D = 5
L = 0
K = 30
U = 126
X = 107

Original formula had one minor error ,so the formulas are not going to work. The equation should be :-

X=120-R*(S-(V/(D/8)))+((R/5)*L)-K+(U-126)/2

X=120-ROUND(R7*(S7-(V7/(D7/8)))+((R7/5)*L7)-K7,0)+(U7-126)/2 (Excel format, numbers in row 7)

I see Brassie has finally arrived.

I did resolve this myself btw. I reckon it's easiest, if you put all numbers in place of letters & then reorganise the equation.
I reckon you make much less mistakes moving numbers around, rather than letters, since you consider what you are doing in each operation better.

Or give them meaningful names, not just a random letter?

I reckon the numbers work better with the mathematic decisions. You can also use excel with the numbers, if you move the terms and check at each stage.