ayudaaaaaaaaaaaaaa por favor

3 - 5 + 3(2-1) + 4 ÷ 2
= 3 - 5 + 3(1) + 4 ÷ 2
= 3 - 5 + 3 + (4 ÷ 2)
= 3 - 5 + 3 + 2
= -2 + 3 + 2
= 1 + 2