Ratio of time and travel

Question

Julie travels 15 mph faster than Derek she can travel 180 miles in the same amount of time that he can drive 135 miles find the two rates

Answer 1

J=D+25

distance = speed times time

time = distance/speed

180/J = 135/D

180/(D+15) = 135/D

cross multiply

180D = 135(D+15) = 135D +2025

45D = 2025

D = 2025/45 = 45 mph for Derek

J = 15+45 = 60 mph for Julie

180/60 = 135/45

= 3 hours for each