Question 905044
STOP spreading out your problems. Preview them before submitting. 
r*t=d
(20+c)*t=60
(20-c)*t=40
20t+c*t=60
20t-c*t=40
add
40t=100
t=10/4
t=5/2=2.5 hours
(20+c)*t=60
(20+c)*2.5=60
20+c=24
c=4 mph