Complimentary angles are angle that add up to 90 degrees :
(2x - 21) + x = 90°
So after factorising:
(2x + x) -21 = 90°
And simplify:
3x -21 = 90°
Do some moving around:
3x = 90° + 21°
3x = 111°
Then divide by 3 on both sides:
x = 37°
Then, because we know what x is, we can substitute it into the formulas for each complimentary angle:
So:
(2x -21) = (2 times 37) - 21 = 53°
And:
x°= 37°
In the questions format:
∠SOT = 37 °
∠SOR = 53°
Hope this helps!
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