A shop sells laptops at $600 each and a smartphone at $400. Celine buys two laptops and four smartphones for her children. How much change does she get back if she has $3000? Give the rationale and then the answer.
Let's think step by step. The cost of the two laptops is 2 x $600 = $1200. The cost of the four smartphones is 4 x $400 = $1600. Thus, the total cost of all the items is $1200 + $1600 = $2800. Therefore, Celine gets a change of $3000 - $2800 = $200.. The answer is: 200.

Sunnyvale School was having a picnic. They wanted to make fruit punch. They had 4.5 liters of orange punch. They had twice as much cherry punch as orange punch and 1.5 liters less of apple juice than cherry punch. When they combined all of the fruit juices together, how many liters of fruit punch did they have? Give the rationale and then the answer.
Let's think step by step. Orange = 4.5 L. Cherry = 2 * 4.5 = 9 L. Apple = 9 - 1.5 = 7.5 L. Total punch = 4.5 + 9 + 7.5 = 21 L. They had 21 liters of fruit punch for the picnic.. The answer is: 21.

James can buy a new computer for $600 and have it last 6 years, or buy 2 used computers for $200 each that each last 3 years. How much money will he save by picking the cheaper option? Give the rationale and then the answer.
Let's think step by step. First find the cost of the two used computers: $200 / computer * 2 computers = $400. Then subtract that cost from the cost of the new computer to find the savings: $600 - $400 = $200.. The answer is: 200.