The punch bowl at Felicia's party is getting low, so she adds 12 cups of punch to the bowl. Two guests serve themselves 1.25 cups and 2 cups of punch. The punch bowl now contains 11.5 cups of punch. How many cups were in the punch bowl before Felicia refilled it? Let n = the number of cups in bowl before Felicia refilled it.
Since we are trying to find the first amount of punch, we work backwards. After two guests serve themselves 1.25 and 2 cups of punch, it is 11.5. This means x-1.25-2=11.5. Add 1.25+2=3.25 to both sides, we get x=14.75. Even before that, she added twelve to the bowl, which is the first action. We give this the variable n, and since it is the first action it will be the answer. n+12=14.75. When we subtract twelve from both sides, we get that n=14.75-12=2.75. Therefore, the number of cups of punch in the bowl before Felicia refilled it, or n, was 2.75 cups.
Hope this helps (ô‿ô).