Question

There are $9$ birds that are chirping and an equal number of birds that are not. Complete the given equation to find the number of birds that are not chirping, and answer which of the following equations is the same as the given equation.

__ $-9=$ __

• A. $8,8+9=17$
• B. $9,10–1=9$
• C. $8,10+8=18$
• D. $9,9+9=18$

Answer 1

The correct option is D $9,9+9=18$

As the number of birds chirping and not chirping are the same, therefore, on two number frames, if we place $9$ counters first and $9$ later, the total counters will be $18$.
Addition equation: $9+9=18$


On two number frames, if we place $18$ counters first and remove $9$ later, the counters left will be $9$.
Subtraction equation: $18–9=9$


Hence, Option A is correct, the number of birds not chirping is $9$ and the addition equation framed is $9+9=18$.