10x + 2y - (4y - 12x)
(when there is a negative sign before the parenteses every sign within the parentheses changes) therefore 4y becomes -4y and -12x becomes 12x
10x + 2y -4y + 12x
Put like terms together
10x + 12x + 2y - 4y = 22x - 2y
Hope this helps.