Answer:
Let's first try to find the angle supplementary to measure 141°.
(Supplementary angles are two angles that add up together to equal 180°).
Set up an equation;
141 + x(unknown angle measure) = 180°
Solve for x:-
141 + x = 180
-141 -141
x = 39°.
Now that we've found one of the interior angles measure to this triangle, we will use this value to figure out the angle measure next to 'x'.
If we think of the line (highlighted in the picture I attached to this), extended, we can kind of make out of this line as a transversal cutting into the two parallel lines(L & M).
Furthermore, the measured angle 39°, is an alternate interior angle with the missing angle next to 'x'(highlighted with yellow in my picture).
And, alternate interior angles are congruent(meaning they measure the same degree).
Therefore, we can infer that the missing angle next to 'x' is also 39°.
Now that we've found one angle measure and another angle(given) next to x, we can see that angle x and those two angle measures (48° and 39°) combined are supplementary!
So now that we know that angles 48° and 39° are supplementary with x, we can find the value of x by finding it's supplement value!
Arrange an equation;
(48 + 39) + x = 180°
Simplify and solve for x:-
87 + x = 180
-87 -87
x = 93°, hence ∠X = 93°.