The midpoint of y and 31 is -5. what is y

Find the solution set of this inequality. enter your answer in interval notation using grouping symbols. |8x-4| ≤ 12

Answer asap ill give ! ’ a sample of radioactive material decays over time. the number of grams, y , of the material remaining x days after the sample is discovered is given by the equation y = 10(0.5)^x. what does the number 10 represents in the equation? a. the half-life of the radioactive material, in days b. the amount of the sample, in grams, that decays each day c. the time, in days, it will take for the samples to decay completely d. the size of the sample, in grams, at the time the material was discovered

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.