<span>So, what you want is the biggest square that can evenly tile a space 240*300. The biggest possible number that can divide 240 and 300. Does that ring any bells? Maybe you should divide 240 and 300</span>
<span>y = x + 3 / 12
This is your answer.</span>
B^2+4
3^2+4
9+4
Your answer is 13.