Answer:
y = 52
Explanation:
4x and 5x lie on a straight line and are a linear pair which sum to 180°
sum the 2 angles, equate to 180 and solve for x
4x + 5x = 180
9x = 180 ( divide both sides by 9 )
x = 20
Then
5x = 5 × 20 = 100°
the exterior angle of a triangle is equal to the sum of the 2 opposite interior angles.
5x = 100° is an exterior angle of the triangle , then
100 = y + 48 ( subtract 48 from both sides )
52 = y