Marisol and mimi walked the same distance from their school to a shopping mall. marisol walked 2 miles per hour, while mimi left an hour later and walked 3 miles per hour. if they reached the mall at the same time how far is the mall from their school?

Let the time in hours after Marisol starts walking be t  and so the time in hours after Mimi starts walking is (t-1)
The distance walked by Marisol=speed*time=2t
Distance walked by Mimi=3(t-1)

When they've reached school they've all walked the same distance so:
3(t-1)=2t
3t-3=2t
3t-2t=3
t=3
Thus the distance from the mall to their school is 2t=2*3=6 miles

For the first question the answer is a, for the second c, for the third d, for the 4th b, for the 5th a