Supplementary angles are angles who's sum is 180 degrees. Knowing this you can make an equation of the unknown angle (let's make this x) plus the known angle (47) equal to 180 like so:
47 + x = 180
To solve for x subtract 47 to both sides
47 - 47 + x = 180 - 47
133
The other angle is B. 133 degrees
Hope this helped!
~Just a girl in love with Shawn Mendes