The half-life of a radioactive kind of neptunium is 7 minutes. If you start with 80 grams of it, which of the following equations represent this
situation?

Aman is 6 feet 3 inches tall. the top of his shadow touches a fire hydrant that is 13 feet 6 inches away. what is the angle of elevation from the base of the fire hydrant to the top of the man's head?

Find the solution of this system of equation -7x+y=-20 9x-3y=36

Calculate the average rate of change over the interval [1, 3] for the following function. f(x)=4(5)^x a. -260 b. 260 c. 240 d. -240