Which of these strategies would eliminate a variable in the system of equations? \begin{cases} 2x + 3y = -5 2x - 3y = 10 \end{cases} ⎩ ⎪ ⎪ ⎨ ⎪ ⎪ ⎧ 2x+3y=−5 2x−3y=10 Choose all answers that apply: Choose all answers that apply: (Choice A) A Add the equations. (Choice B) B Subtract the bottom equation from the top equation. (Choice C) C Multiply the top equation by 222, then add the equations.

A. find the power of the test, when the null hypothesis assumes a population mean of mu = 450, with a population standard deviation of 156, the sample size is 5 and the true mean is 638.47 with confidence intervals of 95 b. find the power of the test, when the null hypothesis assumes a population mean of mu = 644, with a population standard deviation of 174, the sample size is 3 and the true mean is 744.04 with confidence intervals of 95% c. find the power of the test, when the null hypothesis assumes a population mean of mu = 510, with a population standard deviation of 126, the sample size is 10 and the true mean is 529.44 with confidence intervals of 95