Mathamathical Qestion

Question

A teacher needs to buy batteries for 32 calculators.

1. There are 20 basic calculators that each require 3 batteries.
2. There are 12 advanced calculators that each require 4 batteries.
3. The batteries are sold in packages of 24.

The teacher thinks that 6 packages of batteries will be needed and that there will be 12 batteries left over after the calculators are filled. 

Answer 1

How many batteries are required for the basic calculators? (20 x 3 = 60 batteries)

How many batteries are required for the advanced calculators? (12 x 4 = 48 batteries)

What is the total number of batteries needed? (60 + 48 = 108 batteries)

How many packages of batteries are needed? (108/24 = 4.5. However, you can't buy a partial package of batteries. So you must buy 5 packages to have enough)

How many batteries must you buy? (24 x 5 = 120 batteries)

How many extra batteries will you have? (120 - 108 = ??)