Question

Fill in the Blank.

$\left(9+10\right)+\boxed{}=\boxed{}+\left(10+11\right).$

• A. $11$
• B. $9$

Answer 1

If, $a,b,\&c$ are three whole numbers, then $\left(a+b\right)+c=a+\left(b+c\right)$, This property is called the associative property of addition.

$\therefore \left(9+10\right)+\boxed{11}=\boxed{9}+\left(10+11\right).$