1. The problem asks to fill in the box for each expression, which typically means to find the missing value or simplify the expression. 2. Since no specific expressions are given, let's consider a general approach: if the box represents a missing number in an equation or expression, we use algebraic methods to solve for it. 3. For example, if the expression is $x + 3 = 7$, to find the value in the box (which is $x$), we subtract 3 from both sides: $$x + 3 = 7$$ $$x + \cancel{3} = 7 - \cancel{3}$$ $$x = 4$$ 4. This means the box should be filled with 4. 5. If you provide specific expressions, I can help fill in the boxes accordingly.