Hello!
To solve this, you need to distribute and combine like terms.
Like terms are equivalent types of numbers for example;
2x and 3x are like terms, so if the equation said 2x - 5 + 3x, you would only combine 2x and 3x.
If the equation said 5 + 9 - x, you add the like terms, 5 + 9, and the simplification would be 14 - x.
Distribution is when you multiply the number outside the parenthesis into the parenthesis. for example, if an equation says, 5(x-2) = y, you would multiply 5 on the numbers x and -2, resulting in the equation, 5x - 10 = y.
--------Now lets work on your math problem.
Step 1, right the equation, 7(-9a-3)-2a7(−9a−3)−2a
Step 2: distribute numbers (remember multiplying)
7(-9a-3)-2a7(−9a−3)−2a
For the first distribution, 7(-9a-3)-2a7(−9a−3)−2a
you multiply 7 to the numbers in the parenthesis,
resulting in,
-63a - 21
Second distribution is, 7(-9a-3)-2a + 7(−9a−3)−2a
in which you multiply -7 into the numbers in the parenthesis resulting in;
-63a - 21
(did you type the equation twice if so, there are now two problems i need to solve.)
now add like terms -2a + -2a = -4a
-63a - 21 + -63a - 21 = -126a - 42
-126a - 4a - 42
Answer is -130a - 42.
If your equation was actually this, : 7(-9a-3)-2a
Then the answer would have been, -65a - 21