I think the answer is B.
If that's not it, then it must be A.
Answer:

Step-by-step explanation:
(5x^3+4x^2)−(6x^2−2x−9)
To find the opposite of 6x^2−2x−9 find the opposite of each term.
5x^3+4x^2−6x^2+2x+9
Combine 4x^2 and 6x^2 to get −2x^2.
5x^3-2x^2+2x+9
Hey there find an image attached..
Answer:
we can conclude that there is no significant evidence to conclude that the mean score in 2010 differs from the mean score in 2009.
Step-by-step explanation:
H0 : μ = 582
H1 : μ < 582
Test statistic :
T = (xbar - μ) ÷ σ/√n
Xbar = 515 ; n = 20 ; σ = 120
T = (515 - 582) ÷ 120/√20
T = -67 / 26.832815
T = 2.50
Pvalue at t score = 2.50 ; df = 19 is 0.0187
At α = 0.0187
Pvalue > α ; Hence, we fail to reject the Null
Hence, we can conclude that there is no significant evidence to conclude that the mean score in 2010 differs from the mean score in 2009.