SOLUTION: Kylie went on a 126 mile trip to a soccer game. On the way back, due to road construction she had to drive 21 miles per hour slower. This made the trip take 1 hour longer. How fast

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons -> SOLUTION: Kylie went on a 126 mile trip to a soccer game. On the way back, due to road construction she had to drive 21 miles per hour slower. This made the trip take 1 hour longer. How fast      Log On


   

Question 1138433: Kylie went on a 126 mile trip to a soccer game. On the way back, due to road construction she had to drive 21 miles per hour slower. This made the trip take 1 hour longer. How fast did she drive to the soccer game?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
                      SPEED       TIME             DISTANCE

GOING                   r           126/r            126

RETURN                 r-21        126/(r-21)        126

DIFFERENCE                           1

126%2F%28r-21%29-126%2Fr=1

r%2A126-%28%28r-21%29126%29=r%5E2-21r
126r-%28126%28r-21%29%29=r%5E2-21r
126r-126r%2B21%2A126=r%5E2-21r
r%5E2-21r=21%2A126
r%5E2-21r=42%2A63
r%28r-21%29=63%2A42 two factors differ by 21

highlight%28r=63%29