Asample of phosphorus-32 has a half-life of 14.28 days. if 55 g of this radioisotope remain unchanged after approximately 57 days, what was the mass of the original sample?

note: the correct answer is 880 g. i need someone to show me how to get this answer.

After t seconds, a ball tossed in the air from the ground level reaches a height of h feet given by the equation h = 144t-16t^2. after how many seconds will the ball hit the ground before rebounding?

The boiling point of water at an elevation of 0 feet is 212 degrees fahrenheit (°f). for every 1,000 feet of increase in elevation, the boiling point of water decreases by about 2°f. which of the following represents this relationship if b is the boiling point of water at an elevation of e thousand feet? a) e = 2b - 212 b) b = 2e - 212 c) e = -2b + 212 d) b = -2e + 212

Write an inequality for this description. - one fourth of the opposite of the difference of five and a number is less than twenty.