I am unsure of how to do this problem, i don't quite understand the introduction of a fourth variable.
-Brian
"Think of the fourth variable as the 'remainder'. That is, if x1 + x2 + x3 are less than or equal to 11, they could 1, 2, and 3 respectively. Since 1 + 2 + 3 = 6, x4 would be 5, so that x1 + x2 + x3 + x4 (specifically 1 + 2+ 3 + 5) = 11. Then apply the concept we learned about in class dealing with separating pears, apples, and oranges into baskets, or 3 kids pieces of candy." - jnikowit
