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!