Question

find the value of x.

Explanation:

Step1: Recall angle - sum property of a triangle

The sum of interior angles of a triangle is 180°.

Step2: Calculate the third - interior angle of the triangle

Let the third - interior angle of the triangle be $y$. Then $y=180^{\circ}-(87^{\circ}+48^{\circ})=180^{\circ}-135^{\circ}=45^{\circ}$.

Step3: Use the linear - pair property

Since $x$ and $y$ form a linear pair (a straight - line angle which is 180°), then $x = 180^{\circ}-y$. Substituting $y = 45^{\circ}$, we get $x=180^{\circ}-45^{\circ}=135^{\circ}$.

Answer:

$135$