Can somebody please help me answer this question​

Sherina wrote and solved the equation. x-56=230 x-56-56=230-56 x=174 what was sherina’s error? sherina’s work is correct. sherina only needed to subtract 56 from 230. sherina made a subtraction error when subtracting 56 from 230. sherina should have added 56 to both sides of the equation.

Solve the equation - 2(m -30) = -6m a-15 b-13 c-8 d8

Ijust need to see how to do this. so you don’t have to answer all of them just a step by step explanation of one.