Okay just find something the bottom and the top number can be divided by. Like the first one 9/18. They are bithe dividable by 9 so 9÷9=1. 18÷9=2. Now put one back over two. 1/2. So your answer is one half. This is to help you learn how to do it I hope it helps.
Given :
Diameter of pizza ,
.
To Find :
Is square box of size equal to diameter big enough to fit pizza inside it .
Solution :
Area of pizza :

Area of square with side equal to diameter :

Since , the area of square is more than area of pizza .
Therefore , pizza can easily be fitted .
Hence , this is the required solution .
D
Sq rt of 8 is sq rt of 4 times sq rt of 2