Please help I don’t understand how to do this!

Answer:
We can solve this through algebra. So we know two of the angles already which means we can put them in the equation 22+41+3x=90
63+3x=90
Now that we have the equation above, we can solve this through basic algebra.
3x=27
divide both sides by three
x=9 is your answer
Answer:
since, angle RST= 90 degree
therefore, 90= 22 + 41 + 3x
90= 63 + 3x
90 = 3(21 + x)
30 = 21 + x
9 = x