I'm assuming you're trying to simplify the expression? If so, start by combining like terms. 4x+56-57 becomes 4x-1 That is the furthest you can simplify. If it had an equals sign, it would be an equation, and you would solve for x algebraically. But, since there is no equals sign, it is just an expression, and you simplify it to the best of your ability. Hope this helps!
