Solve: 3x - 7 - 2x + 5 = 6

How to do this , and can some one explain

What are the solutions of the equation? z^2 + 11z + 24 = 0 a. 8, -3 b. 8, 3 c. -8, -3 d. -8, 3

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?