A coefficient is the (big) number in front of a number that tells you how many times you multiply the main number

$=(a^2-10a)-(b^2+6b) +16$
$=[(a^2-2(5)a+25)-25]-[(b^2+2(3)b+9)-9]+16$
$=(a-5)^2-25-(b+3)^2+9+16$
$=(a-5)^2-(b+3)^2$
-3n+48=0
-3n=-48
-3n/-3 & -48/-3
n=16
Whats the numbers to solve