Me

7. 9a - 3b

8. (-6m + n) + (-4m - 5n)

9. (9x2 + 5) + (-2x2 - 8) + (x2 - 3)

10. 4a + (9a+3)

11. 7b + (4b - 6)

12. 8d2 + (6d2 - 4d)

13. (5x2 + 4) + (-3x2 - 4)

14. [-4x + (10 - 5x)] + 5x

15. 8 + [5 + (6 + x)]

I’m guessing you needed them factored or simplified?

7. 3(3a-b)

8. -10m-4n

9. 8x^2-6 or 2(4x^2-3)

10. 13a+3

11. 11b-6

12. 14d2-4d or 2d(7d^2-2)

13. 2x^2

14. -4x+10 or 2(-2x+5)

15. 19+x

b.) 160 miles on a 5 gallons car

step-by-step explanation:

240/10=24 miles/gallon

160/5=32 miles/gallon

30/1=30 miles/gallon

168/6= 28 miles/gallon

32 miles/gallon is the most amount, so this is the best.