$$\left(-9\right)+\left(+2\right)=?$$

(a)  

$$\left(-3\right)-\left(+3\right)=?$$

(a)  

$$\left(+3\right)-\left(-4\right)=?$$

(a)  

$$\left(-9\right)-\left(-8\right)=?$$

(a)  

$$\left(-12\right)-\left(-6\right)=?$$

(a)  

$$-2+3=?$$

(a)  

$$4-7+5=?$$

(a)  

□に入る数を答えなさい．

$$\left(-9\right)+□＝-5$$

(a)  

$$\left\{5-\left(1-2\right)+3-4\right\}=?$$

(a)