Question

Justin is on a road trip. Over the past two days, he’s driven a total distance of 504 miles at an average speed of 56 miles/hour. If Justin drove two hours today, he drove miles yesterday.

Answer 1

Recall d  = rt, distance = rate * time.

now, he has a speed rate of 56 mph for a distance of 504

$\bf d=rt\implies 504=56t\implies \cfrac{504}{56}=t\implies \stackrel{hours}{9}=t$

so, at that speed the whole driving time is 9 hours then.  Ok, he drove 2 hours today, that means he drove 7 yesterday, 9 - 2.

how many miles is it for 7 hours at 56mph?  d = rt ---> d = 56 * 7

that many miles he drove yesterday.