Given: 8x-3y = -21, 3x+y = -10; Prove: x = -3 Give the statement and reason using the properties of equality.

Abouncy ball is dropped such that the height of its first bounce is 5.5 feet and each successive bounce is 64% of the previous bounce's height. what would be the height of the 7th bounce of the ball? round to the nearest tenth (if necessary).

Initially 100 milligrams of a radioactive substance was present. after 6 hours the mass had decreased by 4%. if the rate of decay is proportional to the amount of the substance present at time t, find the amount remaining after 24 hours. (round your answer to one decimal place.)

Select true or false to tell whether the following conditional p q is true or false. use the truth table if needed. if a week has seven days, then a year has twenty months.