Answer:
∴ x = 10.7 (to 3sf), y = 18
Explanation:
(3x)° + (4x-15)° = 90° (right angle given) ------ equation (1)
(3x)° + (4x-15)° + (5y)° = 180° (adjacent angles on a straight line) ------ equation (2)
From equation (1),
3x + 4x - 15 = 90
7x = 75
∴ x = 10.7 (to 3sf)
Subtract equation (1) from equation (2):
(3x+4x-15+5y) - (3x+4x-15) = 180 - 90
5y = 90
∴ y = 18