a) 25.8
b) 36.8
c) 64.2
d) 42.0

Answer:
y = 25.8
Step-by-step explanation:
Since this is a right triangle, we can use trig functions
cos y = adjacent/ hypotenuse
cos y = 18/20
Take the inverse cos of each side
cos ^-1 (cos y) = cos^-1(18/20)
y =25.84193276
Rounding to the nearest tenth
y = 25.8