Answer:
7a + b - 16c
Explanation:
So we have
7a-3b+c-8c+4b-9c
When it comes to problem like these, you need to combine like terms.
There's only one 'a' number, so that one remains the same.
Next, we have -3b and 4b. (-3b+4b)= b
Finally, there's (c-8c-9c).
(-8c-9c)= -17c
Take that and add the positive 'c' to it.
(-17c+c)= -16c
Put it all together now to get:
7a + b - 16c
I hope that helped and helped you understand at least a little
:)