SAT Circles Question

Circle A shown is defined by the equation $x^2+(y-5{)}^2=7$. Circle B (not shown) has the same radius but is translated 91 units to the right. If the equation of circle B is $(x-h{)}^2+(y-k{)}^2=a$, where $h$, $k$, and $a$ are constants, what is the value of $4a$?