Trigonometry.
We must use the SOH CAH TOA rule to find the missing angle, x.
Given that the two known sides: opposite to angle x is 7 and the adjacent side to angle x is 11, we use the tan sign because tan is for TOA which is (opposite/adjacent).
So we can write the equation like this:
tan(x)= 7/11
To get x, inverse tan on calculator:
Tan^-1 (7/11) = 32.4711...
Round it off = 32 degrees.