Jeremy bought postcards on a trip. He sent 5 cards to his aunt. He sent half of
the remaining cards to friends. Then he
sent one of the remaining cards to his
sister. He was left with 4 cards. Write
and solve an equation to find out how
many postcards Jeremy bought.

An automated water dispenser fills packets with one liter of water on average, with a standard deviation of 5 milliliter. the manual says that after a year of operation the dispenser should be tested to see if it needs recalibration. a year later a number of filled packets are set aside and measured separately. it is found that the average packet now contains about 0.995 liters. does the dispenser need calibration? explain your answer.

Saline iv fluid bags cost $64.20 for 24, 1000 ml bags from one supplier. a new supplier sells 500 ml bags for $2 each. the hospital uses about 10,000, 1000 ml bags each month. nurses report that about half of the bags are more than half full when they are discarded. if you are going to use only one supplier, which size bag provides the best deal, and how much will you save each month? compare the cost of the new supplier to the current one.

What is the solution to this system of equations? y= 2x - 3.5 x - 2y = -14