Answer:
60
Step-by-step explanation:
Supplementary angles add up to 180 degrees
If ∠C and ∠D are supplementary, then ∠C + ∠D = 180
This means that (x + 25) + (2x - 25) = 180
(x + 25) + (2x - 25) = 180
==> remove parenthesis
x + 25 + 2x - 25 = 180
==> combine like terms
3x = 180
==> divide both sides by 3
x = 60