Given the expressions
This is an equation system with two unknowns, to solve it the objective is to replace one equation into the other so that the final expression has only one unknown.
The first expression indicates you the y is equal to "-3x+4", if you replace this equivalency in the second equation, where the y-term is, you get that
Now we have an expression with one unknown, "x", and we can solve it for x. That is, we have to isolate the x-term alone in one side of the equal sign and all other terms need to be on the right side
1) Solve the multiplication on the parentheses term by applying the distributive property of multiplications