First we have to find how long it takes Ahmad to run 1 mile.
So,
A) 80 min will be divided by 7 miles-
80/7 = 11.43 min/ mile
Ahmad runs 1 mile in approximately 11.43min.
B) How long will he run in 64 min?-
Since we know that it takes 11.43min to run 1 mile, we will divide 64 by that 1 mile time.
64/11.43 = 5.6 miles in 64 min.
Our answer is: Ahmad will run 5.6 miles in 64 min.
Another way to solve this, is by cross multiplying:
A)7/80 • x/64 = 448/80x. Now, solve for x by...
B) 448/80 = 5.6
5.6 miles
Hope that helped you understand.