Eugene had some paper with which to make cards. On his way to his room he found three more pieces to use. In his room he cut each piece of paper in half. When he was done he had 12 half-pieces paper. With how many pieces of paper did he start?

In order to find the price per bar, we divide the price by the amount of bars.   for the first one: 15.37/10 = $1.54 per barthe second package: 15.35/12 = $1.28 per bar.the 10-pack costs $1.54 per bar and the 12-pack costs $1.28 per bar.   the 12-pack has the better price per bar.now, let's look at the price per ounce.   we do this in a similar way.   we find the total amount of ounces in the package, and divide the price by the number of ounces.in the first package, we multiply 10*2.1=21.   we have 21 ounces in the first package.   now we divide 15.37/21.   in the first package, we have 0.73 dollars per ounce.now, let's look at the second package.   we start by multiplying 1.4*12=16.8.   there are 16.8 ounces in the package.   now, we divide 15.35/16.8=0.91.   so, in the second package, we have 0.91 dollars per ounce.the cost per ounce of the 10-pack is $0.73 and the cost per ounce of the 12-pack is $0.91.   the first package has the better price per ounce.the better explanation is the second one, because i prefer the lower price per ounce, i think that the 1st pack is the better buy.