truck leaving St. Louis

Question

A truck leaves St. Louis Missouri traveling north on I 55 at an average rate of 47 mph. One hour later a bus leaves St. Louis traveling south on I 55 at an average rate of 54 mph. How long after the truck leaves will it take until they are 552 miles apart?

Answer 1

d=r*t

d=47t north

d=54(t-1) south

552=47t+54(t-1)

552=47t+54t-54

552+54=101t

606=101t

t=606/101

t=6 hours after the truck leaves

check: 6*47=282, 5*54=270, 282+270=552 miles

Answer 2

d = 47t represents the distance that the truck can cover

d = 54t represents the distance that the bus can cover

47t + 54t = 552

101t = 552

t ≈ 5.465 hours

 

I didn't know how you wanted to round the answer.