Question 401240
Beverly can drive 600 miles in the same time Susan can drive 500 miles. If Beverly can drive 10 mph faster than Susan, how fast does Beverly drive? i know this is the D=r*t formula, but the answer I got was 1/2. so i just think i have the set up the equation wrong. 
.
Let x = time driven by Beverly and Susan
and y = speed of Susan
then
y+10 = speed of Beverly
.
from:"Beverly can drive 600 miles"
x(y+10) = 600 (equation 1)
.
from:"Susan can drive 500 miles"
xy = 500 (equation 2)
.
Solve equation 2 for x:
x = 500/y
.
Substitute above into equation 1:
x(y+10) = 600
(500/y)(y+10) = 600
500(y+10) = 600y
500y+5000 = 600y
5000 = 100y
5000/100 = y
50 mph = y (speed of Susan)
.
Beverly's speed:
y+10 = 50+10 = 60  mph