7(3x + 2) = 18 - (x + 48)
Distribute on both sides. On the left side, multiply each term in parentheses by 7. On the right side, a negative sign to the left of parentheses is as if a -1 is there, and you must multiply everything inside the parentheses by -1.
7(3x + 2) = 18 -1(x + 48)
21x + 14 = 18 - x - 48
21x + 14 = -x - 30
22x = -44
x = (-44)/22
x = -2
Answer: x = -2