What are these about ? can anyone explain to me this part? : (

The answer is 45 degrees

The reciprocal of any function is 1 over the function 

for example, the reciprocal of 

So
if x + y = 90 

The value of x and y should be the same bcz

 means that the function is reciprocal and the measure of their angles (x and y) have to be the same

45 + 45 = 90

x = 45
y = 45