Calculate average mph

Question

Barbara left Amanda's house heading toward the ocean. One hour later,Amanda left driving 8mph faster than Barbara in an effort to catch up with her. After four hours, Amanda caught up with Barbara. What was each woman's average rate

Answer 1

d = rt, and since the distances were the same. If r = Barbara's rate...

 

4(r + 8) = 5r

4r + 32 = 5r

r = 32

 

Amanda was going 32 + 8 = 40 mph.

 

Let's check.

 

4(40) = 5(32)

160 = 160

 

Check!