It takes Heidi 10 minutes to get to school going at a speed of 27 miles/hour. How long will it take her to get to school if she goes 40miles/hour?

The distance to the school is: 27 miles/hour x (10/60) hours = 27(1/6) = 4.5 miles. 

The time it will take her to get to school if she goes 40 miles/hours is: t = d/v = 4.5 miles/40 miles/hour = 0.1125 hour = 6.75 minutes.