What is the value of Y

y = 150º

Step-by-step explanation:

The sum of internal angles of a triangle must be 180º and the sum of y + (x-20) forms a straight line which is also 180º, so:

2x + x + (x - 20) = 180

4x - 20 = 180

4x = 200

x = 50

x - 20 = 50 - 20

x - 20 = 30

y = 180 - 30

y = 150º

47 - 90 = 43

43 - 180 = x

x = 137