Question

Use the three steps to solve the problem. Express the answers using decimals. It took John 12 hours riding his bike to make the round trip to his uncle's. If he averaged 20 mph out and 30 mph back, how long did he travel each way? (Round answer to nearest tenth.) {Out a0 hrs., back a1 hrs.}

Answer 1

x - time travel out
(12-x) = time travel back

distance  to the uncle's house =20x
distance back =30(12-x)

Because distance  to the uncle's house and distance back are the same, we can write
20x=30(12-x)
20x=30*12 - 30x
20x=360 - 30x 
30x+20x =360
5x=36
x=7.2  h time travel out
12 - 7.2=4.8 h time travel back

a0 = 7.2h
a1= 4.8h