$$x-(90-x)= \frac{ (180-x) }{ 4 }$$
$x=60$
$$4x-4\left(90-x\right)=180-x$$
$$4x-360+4x=180-x$$
$$8x-360=180-x$$
$$8x-360+x=180$$
$$9x-360=180$$
$$9x=180+360$$
$$9x=540$$
$$x=\frac{540}{9}$$
$$x=60$$
Show Solution
Hide Solution