First you set up an equation using a variable:
x + 5x = 90° (complementary angles = 90°)
6x = 90
x = 15 (also the measure of the smaller angle)
now plug in x to find the larger angle:
5(15) = 75°
The discriminant of this equation is 49. The solutions for this equation are x=2 and x=-

I hope that helps.
Given:
Consider the below figure attached with this question.
To find:
The value of
.
Solution:
The given functions are:


Now,




We know that,

Adding 3 on both sides, we get


So,
for all values of x.
Hence, the correct option is A.
QS would be 42. So the way i did it was I:
8x-51=3x-6
x=9
Plugged into both equations of QR and RS to then get the answer of 42