Answer:
20
Step-by-step explanation:
The question tells us that line a is parallel to line b (even if they don't seem to be in the image).
∠8 = ∠4 and ∠5 = ∠1 since line t crosses the parallel lines.
We are given ∠4 = 3x and ∠5 = 6x.
Since we know ∠8 = ∠4 , we can then say
∠8 = 3x and ∠5 = 6x
Since ∠8 and ∠5 are complementary and combined they form a flat angle of 180 degrees, we can say:
3x + 6x = 180
9x = 180
x = 20
