Answer:
x = 4
Step-by-step explanation:
To begin, first find Angle SUT.
Knowing that SUH is a straight line, Angle SUT plus 100 degrees should equal 180 degrees. Angle SUT is 80 degrees.
The sum of all the degrees in a triangle is also 180 degrees.
SO
(4x + 4) + (21x - 4) + 80 = 180
25x + 80 = 180
25x = 100
x = 4
