Answer:
Explanation:
Let the speed of the cars be x and y.
When moving in opposite directions, the speeds add up and when moving in the same direction the speeds subtracted.
Convert time from minutes to hour:
- 4 minutes = 4*1/60 hr = 1/15 hr
- 20 minutes = 20*1/60 hr = 1/3 hr
Opposite direction
- (x + y)*1/15 = 8
- x + y = 8*15
- x + y = 120
Same direction
- (x - y)*1/3 = 8
- x - y = 8*3
- x - y = 24
Add up the two equations and find the value of x:
- x + y + x - y = 120 + 24
- 2x = 144
- x = 72
Find y:
- 72 + y = 120
- y = 120 - 72
- y = 48