Linear equation word problem

Question

Mary and Janet are running in the Apple hill fun run. Mary runs at 7mph, Janet at 5mph. If they start at the same time, how long will it be before they are 1.5 mi apart

Answer 1

Distance = (Rate)(Time)

Distance travelled by Mary in x hours = 7x

Distance travelled by Janet in x hours = 5x

They will be 1.5 miles apart when 7x - 5x = 1.5

2x = 1.5

x = 0.75 hours

They will be 1.5 miles apart after 45 minutes.

Answer 2

M = 7.5 X => (M is total distance she ran, x is total hours she ran)

J = 5 X => ( J is total distance she ran, x is total hours she ran)

M - J = 1.5

7.5 x - 5 x = 1.5

1.5 x = 1.5

x = 1

1 hour later they will be 1.5 mi apart