A store sells batteries in packets of 6 or 10. It has a stock of 25 packets containing a total of 186 batteries. How many of these are 10-battery packets?

Question

anonymous · Answer

you are looking for a balance in the numbers, so ...
you need to have 186 batteries total and since 6 is more challenging, you need to find its multiple that corresponds (6;12;18;24;30;36; etc) and then use the multiple of 10 to make up for the rest so that all the requirements are met of 25 packets and 186 batteries.

6*16 + 10*9 = 186 batteries and 25 packets.