Hi, I am needing some help on this question. I am not understanding where to start and how to find the answer.

Question

Find the value of x. The diagram is not to scale. Given: ∠SRT ≅ ∠STR, m∠SRT = 20, m∠STU = 4x

Answer 1

∠ SRT = ∠STR, and m ∠SRT = 20,

m ∠STU = 4x

∠STR + ∠STU = 180° (Sum of angles on a straight line)

Since ∠ SRT = ∠STR, and m ∠SRT = 20,

∠STR = 20

∠STR + ∠STU = 180° becomes

20 + 4x = 180

20 - 20 + 4x = 180 - 20

4x = 160

∴ x = 160 ÷ 4

x = 40