Usually when you do expressions involving subtraction you can do Keep, Change ,Change
That means you keep the sign of the first number and change the other two signs.
It is best you rewrite the expression to addition because a lot of people don't do well with subtracting .
4 bc you can make 1/2 into 2/4 and they would all have a denominator of 4
The largest square you can make using 40 tiles, would be 100
