Question

Solve using absolute values.

$(+21)+\_\_\_\_=17$

Answer 1

Let the missing number be $x$, then,

$$\begin{gathered} (+21)+\_\_\_\_\_\_=17 \\ \Rightarrow 21+x=17 \\ \Rightarrow x=17-21 \\ \Rightarrow x=-4 \end{gathered}$$

Hence, the missing number is $-4$.