Answer:
x = 5
Step-by-step explanation:
Using the cofunction identity
sin x = cos(90 - x), then
12x + 18 = 90 - (3x - 3), that is
12x + 18 = 90 - 3x + 3 ( add 3x to both sides )
15x + 18 = 93 ( subtract 18 from both sides )
15x = 75 ( divide both sides by 15 )
x = 5
