Distance = change in velocity*change in time
We can find the distance to her grandmas house by plugging in the know info.
Her velocity is 50MPH and her change in time is 3 hours and 3 minutes. Change those minutes into hours by diving by 60 minutes. 3/60 = 0.05 hours. So her total time is 3.05 hours. Do 3.05 hours times the 50MPH, notice the hours cancel and you get miles, 152.5 miles.
Now in the second problem, they give rate but we want time now. And we just solved the distance.
152.5 miles = 53MPH(t)
T being the time it takes
Divide the two numbers and the miles unit cancels, and you’re stuck with hours, 2.88 hours.