If a jet flyes directly over you house after taking off from the airport and flyes approximately twelve miles how many miles high is the jet when it flies over your house?

The answer will be different for every jet based on multiple factors; the weather, the speed of the jet at take-off, the angle in which the jet is ascending and the size/weight of the jet and items or people in the jet. Most commercial planes will not fly more than 7-8 miles above ground due to the thin atmosphere not being able to support the jet. Depending on the situation, between 5-8 miles above the house would be a solid estimate.