The half–life of rubidium–89 is 15 minutes. if the initial mass of the isotope is 250 grams, how many grams will be left after 100 minutes? a. 2.46 grams b. 0.0098 grams c. 0.90 grams d. 225.31 grams

Find a number such that if you add 8 and divide the result by 4 you will get the same answer as if you subtracted 3 from the original number and divided by 2

Sum is 17 and their difference is 3

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?