An element with a mass of 630 grams decays by 30% per minute. To the nearest minute, how long will it be until there are 30 grams of the element remaining?

When solving this problem: 3025/5.5 = a/90.75 you get 49912.5 which would be the length of one of the sides of a square when the area is only 90.75 inches. is that answer correct, why, and how is it possible?

Yvaries inversely as x. y =12 when x=5. find y when x=4

Marco states that 7.696696669…… is a rational number because it is a repeating decimal. is he correct? justify your answer.