SOLUTION: 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

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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.
Answer by nerdybill(7384) (Show Source):
You can put this solution on YOUR website!
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