Name the property that proves these triangles are congruent

In the polynomial below, what number should replace the question mark to produce a difference of squares? x2 + ? x - 36

You dug a hole that was 8 feet deep. after taking a short break, you dug down 3 more feet in the same hole. when finished digging, a tractor accidentally filled the hole with 4 feet of dirt. how deep is your hole now?

An elevator travels 310 feet in 10 seconds. at that speed, how far can't his elevator travel in 12 seconds?