Question

Angles X and Y are supplementary. Angle X is 3 times the measure of angle Y. What is the measure of angle X?

Answer 1

3x + x = 180

4x = 180

x = 45

Angle y  = 45

Multiply 45 * 3 = 135

<x = 135

Answer 2

we know that

Supplementary angles are those angles whose sum is equal to $180$ degrees

In this problem

$x+y=180$ --------> equation $1$

$x=3y$ --------> equation $2$

Substitute the equation $2$ in equation $1$

$[3y]+y=180$

$4y=180$

$y=45$°

Find the value of x

$x=3*45$

$x=135$°

therefore

the answer is

The measure of angle x is $135$°