Question 100290
distance(d)=rate(r) times time(t) or d=rt;  r=d/t and t=d/r

Let t=time it took Lois to ride home in the car
Then (t+1.5)=time it took Lois to bike to her friends

(1)  distance she travelled on a bike=rt=10*(t+1.5)
(2)  distance she travelled back in the car=25*t

Now we know that (1)distance going=(2)distance coming back in the car.  So:

10(t+1.5)=25t  get rid of parens

10t+15=25t  subtract 10t from both sides

10t-10t+15=25t-10t  collect like terms

15=15t  divide both sides by 15

t=1 hour time it took to ride home in the car

t+1.5=1+1.5=2.5 hrs-------------------------time it took biking to her friends

CK

2.5*10=1*25
25=25


Hope this helps----ptaylor