Can someone me with this and explain: compute 28p7

Can you answer my question? will mark brainiest!

In factoring by grouping, what would you have for step 3 for the following? step 1: x^3 +5x^2 +4x+20 step 2: x^2 (x+5)+4(x+5) step 3: ?

2x - 20 = 32 20 - 3x = 8 6x - 8 = 16 -13 - 3x = -10