Answer :
-7cd²
1) Subtracting -2 cd² from -9cd² we have:
-9cd² - (-2cd²) A minus prior to the parentheses changes its sign
-9cd² + 2cd² Proceed with the operation
-7cd²
2) Hence, the answer is -7cd²
-7cd²
1) Subtracting -2 cd² from -9cd² we have:
-9cd² - (-2cd²) A minus prior to the parentheses changes its sign
-9cd² + 2cd² Proceed with the operation
-7cd²
2) Hence, the answer is -7cd²