Thread: velocity problem

ok, here is the math problem

A plane can fly 315 mph in still air. If it can fly 190 miles downwind in the same amount of time it can fly 125 miles upwind, find the velocity of the wind.

and i got the formula to the set up of

(315+x)*T=190
(315-x)*T=125

now what do i do from here

Originally Posted by Riloblade

ok, here is the math problem

A plane can fly 315 mph in still air. If it can fly 190 miles downwind in the same amount of time it can fly 125 miles upwind, find the velocity of the wind.

and i got the formula to the set up of

(315+x)*T=190
(315-x)*T=125

now what do i do from here

Very good with those two equations.
Now solve those simultaneously.

You don't want to know the T, so eliminate T either by substitution or by division.

By substitution;
From the first equation,
T = 190 /(315 +x)
Substitute that into the second equation,
(315 -x)*[190 /(315 +x)] = 125
190(315 -x) = 125(315 +x) ------**

Maybe you can continue from there.

--------------------------------------
By division:
Divide the first equation by the second equation,
(315 +x) /(315 -x) = 190 /125
Cross multiply,
125(315 +x) = 190(315 -x) -----same as the above.

Originally Posted by Riloblade

does this problem make sense to anyone?

A plane can fly 315 mph in still air. If it can fly 190 miles downwind in the same amount of time it can fly 125 miles upwind, find the velocity of the wind.

i think the set up problem is this (315+x)*T=190 Mr F says: => T = 190/(315 + x) .... (1)

(315-x)*T=125 Mr F says: => T = 125/(315 - x) .... (2)

i don't know what to do after this

please help

Equate equations (1) and (2) and solve for x.