The first step for solving this expression is to remove the first set of parenthesis.
8j³ - 10j² - 7 - (6j³ - 10j² - j + 12)
When there is a "-" sign in front of the parenthesis,, you must change the sign of each term in the parenthesis. This will look like the following:
8j³ - 10j² - 7 - 6j³ + 10j² + j - 12
Eliminate the opposites in the expression
8j³ - 7 - 6j³ + j - 12
Collect the first set of like term (ones with j³)
2j³ - 7 + j - 12
Calculate the difference between basic numbers
2j³ - 19 + j
Lastly,, use the commutative property to reorder the terms
2j³ + j - 19
Since you cannot simplify this expression any further,, the correct answer to your question is 2j³ + j - 19.
Let me know if you have any further questions
:)