What is the prefix in regroup? what dose it mean?

Consider the proof. given: segment ab is parallel to line de. prove: what is the missing statement in step 5?

Solve the following simultaneous equation by using an algebraic method (either substitution or elimination) 2x + 3y=-4 4x-y=11

Hell . what are the solutions to `10x^2 - 38x - 8 = 0`? is this when i find the factors and use the numbers within the factors to determine the zeros? i hope that made sense lol