The answer would be letter c because you have to use orders of operations io on aka A^2+B^2=C^2 how to set it up woulf look like this: a^2= 7^2 B^2=?, and C^2=13^2 in other words a=7squared B=? and C=13 squared so the problem would end up like this:.7*7+B*2=13*13 49+B*2=169 so now you subtract 169 from 49 and that equals B*2=√120