Explanation:
Part 1: 4x + 7 = 3(2x - 5)4x+7=3(2x−5)
4x+7=6x-154x+7=6x−15
7=6x-15-4x7=6x−15−4x
7=2x-157=2x−15
7+15=2x7+15=2x
22=2x22=2x
22=2x / 222=2x/2
x=11x=11
Part 2: Sam is not correct because he messed up the second step. He added 2x on both sides to get 7x, instead he should have subtracted.