I am not completely sure but Khan Academy might show how to do that. Or it might at least give an example.
Answer:

in a graph the x value at the y intercept is 0
is a typical decay function
if x = 0 thus
= 1
so at 0 the function value would be A

Step-by-step explanation:
92 degrees
Triangle= 180 degrees
180-60-28= 92
:)