Question 797194
The sum of the speeds of two cars is 724.3 mph.
x + x = 724.3  
If the speed of first car is 7.7 faster than the second.
x + 7.7x = 724.3
8.7x = 724.3
x = 724.3/8.7
x = 83.3 mph
Slower car = 83.3 mph.
Faster car = 641.0 mph.
Hope this helps.
:-)