How fast did she drive going to the camping spot?

Question

Mary drove 4 hours to reach her camping spot. Driving home, she increased her speed by 15 miles per hour, reducing her travel time by 1 hour.

Answer 1

d=rt

d=r*4 going

d=(r+15)*3 coming back

4r=3(r+15)

4r=3r+45

4r-3r=45

r=45 mph answer

check: 45*4=180 miles

          60*3=180 miles