Find and explain the error in the solution given. 4 (x+3) = 40 4x+12=40 4x+12+-12=40-12 4x=28 4x over 4=28*4 x=112

Your formatting is a bit odd, but it looks like the student went from 4x = 28 to x = 112, which is incorrect. If I'm reading that right, then the error is in that last step. The answer should be x = 7. You divide both sides by 4 to go from 4x = 28 to x = 7. The student or teacher must have multiplied 28 by 4 on accident.

note: replace x with 7 and we can check the answer

4 * (x+3) = 40

4 * (7+3) = 40

4*10 = 40

40 = 40

We get a true equation, so the answer is confirmed