jack ran a 15 000 meter race in 1.8 hours. if he runs 20 km at the same speed how many extra minutes will it take to complete the race

We can set this up as a proportion problem.

1.8/15 = x/20       So taking the cross- product, we have

20 * 1.8 = 15 * x    Divide by 15 on each side

20 * 1.8 / 15 =  2.4 hours

So

(2.4 - 1.8) = .6 hrs. = (.6 * 60minutes) =  36 minutes