40. The two assumptions I'm making: 1) Each box contains the same number of balloons. 2) Porch is considered part of the yard, outside the house. Let

40. The two assumptions I'm making: 1) Each box contains the same number of balloons. 2) Porch is considered part of the yard, outside the house. Let N be the number of balloons in each box. We have 2N balloons. We are told that N of them were used outside the house ("He used half of them to decorate his yard." or 2N/2 = N.). Specifically, we know that "He used 40 to decorate his porch." Therefore, N = 40. "He used the rest inside his house." We have N left, so N were used inside the house. N = 40. This is the literal interpretation of the words. But, 40 isn't one of the available answers, so let's try again. ### What the question was probably assuming is that the yard is separate from the porch. Starting over, let's treat our total amount of balloons as B, and N is the balloons in each box, so B = 2N. We know that half were used in the yard (call this B/2), which is separate from the porch. 40 were used on the porch, so B/2 + 40 in total used outside, and the rest used inside (call this Y). B - B/2 - 40 - Y = 0 What value of Y here (one of the 4 answers) gives us a value for B where B = 2N? 60. B/2 - 40 - 60 = 0 B/2 = 100 B = 200 = 2N N = 100