91Ó°ÊÓ

According to subtraction property, the subtraction of a number is equal to the addition of its opposite. This can be expressed as follows.

$a-b=a+\left(-b\right)$

Add the opposite of 7 to 13.

$\begin{array}{rcl}13-7& =& 13+\left(-7\right)\\ & =& 6\end{array}$

According to subtraction property, the subtraction of a number is equal to the addition of its opposite. This can be expressed as follows.

$a-b=a+\left(-b\right)$

Add the opposite of 13 with the opposite of the opposite of 7.

$\begin{array}{rcl}-13-\left(-7\right)& =& -13+7\\ & =& -6\end{array}$

According to subtraction property, the subtraction of a number is equal to the addition of its opposite. This can be expressed as follows.

$a-b=a+\left(-b\right)$

Add the opposite of 7 with the opposite of 13.

$-13-7=-20$

According to subtraction property, the subtraction of a number is equal to the addition of its opposite. This can be expressed as follows.

$a-b=a+\left(-b\right)$

Add 13 with the opposite of the opposite of 7.

$\begin{array}{rcl}13-\left(-7\right)& =& 13+7\\ & =& 20\end{array}$