Please generate 20 unique math quizzes for me.

Requirements:

1. the operator can either be add or subtract
2. the at least one of the operands and the result should be a negative number
3. the operands must be between -30 and 30
4. the final result must also be between -30 and 30

Example:
15 - (-15) = 30
(-11) + (-16) = -27
2 - 18 = -16