I chose 3 since the equation usually contains of 3 numbers however it is the wrong answer. I know it’s 2 but it doesn’t say it there. Someone help pls ㅠㅡㅠ

I chose 3 since the equation usually contains of 3 numbers however it is the wrong answer I know its 2 but it doesnt say it there Someone help pls ㅠㅡㅠ class=