gcse math

So we need to know that S=D/T, where D = 5 miles and T = 15 minutes. But we want average speed in mph im assuming therefore we need to change the 15 minutes into hours. We do this by doing 15/60 which is 0.25 hours. Now we substitute our two values for D and T into the formula to find S. So 5/0.25 = 20 mph

ahhhh i understand now.... thank you!