Question

Charlie drove 864 miles in 12 hours. at the same rate, how long would it take him to drive 504 miles?

Answer 1

We can solve this by setting up a proportion where 864/12 = 504/x. We cross multiply and get 864x = 504 * 12. So 864x = 6048. Divide by 864 on both sides, x = 7.

It would take Charlie 7 hours to drive 504 miles. 

Answer 2

The answer is 7 hours.

The formula for this is Speed = Distance/Time. Time = Distance/Speed

864miles/12hrs = 72mph

With the same formula plug in 504 miles for Distance and leave time as X and speed will be 72mph.

72mph = 504miles/x 
Cross multiply
72x = 504
Divide by 72
X = 7 hours