What belongs in the box marked with the question mark in the proof?Given: 3x - 4 = 2(x + 8), Prove: x = 20StatementReason(1) 3x - 4 = 2(x + 8)(2) 3x - 4 = 2x + 16(3) 3x = 2x + 20                                               (?)(4) x = 20

(1) 3x - 4 = 2(x + 8) ..............Given
(2) 3x - 4 = 2x + 16...............Distributive property
(3) 3x = 2x + 20-----------------Addition property of equality
(4) x = 20-------------------------Subtraction property of equality