A car starts at 7 AM and travels at 80 kph Another car start

A car starts at 7 AM and travels at 80 kph. Another car starts at 10 AM from the same place and goes in the same direction. How fast will it have to go to catch up with the first one by 4 PM of the same day?

Solution

80 = car 1 rate
x=car 2 rate
the distance when car 2 overtakes car 1 will be equal
the time for car one is 9 hours
the time for car two is 6 hours
rate*time=d
because the distance for both is the same we have two equations we can set equal to one another:
80(9)=x(6)
720=6x
120=x
car two must travel 120 kmh