I need some help, anyone with a explanation on how to do this any help is appreciated:)

Answer:
12.6
Step-by-step explanation:
Pythagorean theorem: a^2+b^2=c^2
you are given c & b you have to find a so
c^2-b^2=a^2
196-36=160
take the square root of 160
12.6 is the final answer :)