2g^3+24g^2-g-1 is the answer
Answer: 
<u>Step-by-step explanation:</u>

9x – 3y – 5x + 7y + x + y
9x-5x+x -3y+7y+y
x(9-5+1) +y(-3+7+1)
5x+5y
Choice C
Answer:
A, B and C
Step-by-step explanation:
To determine which ordered pairs are solutions, substitute the x and y coordinates into the system of equations and if the value equals the right side then the ordered pair is a solution
A (6 , 3 )
(3 × 6) - 3 = 18 - 3 = 15 ← correct, and
(6 × 6) - (2 × 3) = 36 - 6 = 30 ← correct
Hence (6, 3 ) is a solution
B (7, 6 )
(3 × 7) - 6 = 21 - 6 = 15 ← correct, and
(6 × 7) - (2 × 6) = 42 - 12 = 30 ← correct
Hence (7, 6 ) is a solution
C (8, 9 )
(3 × 8) - 9 = 24 - 9 = 15 ← correct, and
(6 × 8) - (2 × 9) = 48 - 18 = 30 ← correct
Hence (8, 9 ) is a solution