To simplify this expression, you have to distribute. Distribution is when you multiply the outside number by the inside ones. For example, if I distributed 2(4 + 6), I would get (2 × 4) + (2 × 6).
So if we distribute your expression, we'd get: (-3 × -4y) + (-3 × 3) + 7y Now simplify: 12y + -9 + 7y Once more, simplify: 19y - 9