NEED ASAP!!!
how do i do this and whats the answer?

Answer
The answer is 148*
Step-by-step explanation:
Ummm This is because The total amount of degrees in a triangle will ALWAYS(No matter what) be 180* Degrees. So i subtracted 12 and 20 from 180. that was.. 148.
i think.
Make sure to get more answers before you trust mine.
The answer is 16
12^2+b^2=20^2
144 + b^2= 400
B^2= 256
Square root of 256 is 16