A delivery person uses a service elevator to bring boxes of books up to an office. The delivery person weighs 150 lb and each box of books weighs 60 lb. The maximum capacity of the elevator is 1580 lb. How many boxes of books can the delivery person bring up at one time?

23 boxes of books

Step-by-step explanation:

23 X 60 = 1380

1380 + 150 = 1530

You can't have any more or it will go over

ending amount = beginning amount / (2^n)

where "n" = number of half-lives (or elapsed time / half-life)

ending amount = 50 mg / (2 ^10 / 5.3)

ending amount = 50 mg / (2 ^ 1.8867924528)

ending amount = 50 m / 3.6981210597

ending amount = 13.5203794557 mg

or about 13.5 mg remain

source:  

the anwser is x< -17/2