Answer: the rules are 
 
+(+) Two like signs become a positive sign 
−(−) 6−(−3) = 6 + 3 = 9
+(−) Two unlike signs become a negative sign 
−(+)
Explanation:
Example: 3+(+2) = 3 + 2 = 5, 6−(−3) = 6 + 3 = 9, 7+(−2) = 7 − 2 = 5,8−(+2) = 8 − 2 = 6 hope this helps you :)