so basically if we say that rolls are represented by x and wrapping paper is represented by y, we can say x plus y is 125 because there are a total of 125 rolls and packages. if each roll is 3.50 and each package is 2.25, we can just put each number in front of the corresponding variable to show that each one is worth that amount, and they total to 347.50. then you have to solve the system of equations. so if you solve for x in the first equation, x = 125 - y. so plug that in to the next equation, 3.50(125 - y) + 2.25y = 347.50. solve for y and you get 72.
but y is the number of packages, and we want the number of rolls. there are 125 rolls and packages, so 125 minus the 72 packages and you get 53 rolls
