The picture is too small, but which equations can undo each other?
Addition and Subtraction is Inverse Operations
Multiplication and Division is Inverse Operations
Angle 11 is 119
and select alternate interior angles theorem
arcsin(1/2) means "the angle whose sine is 1/2".
That's 30° .
y = cos(30°) = (1/2)√3 = about 0.866 .
Discriminant = b^2 - 4ac
a = 4
b = 16
c = 16
16^2 - 4(4 x 16)
256 - (4x64)
256 - 256 = 0
Therefore it only has one root
2 and 3
negative numbers won't work, nor will 0
1 and 2 won't work because 1*8=2*4
2 and 3 is the answer