How many distinct sums can be obtained by adding three different numbers from the set {3, 6, 9, ... ,27 , 30 \(, 33, 36, 39, 42\)}?
+240 Its just the multiples of 3 from the smallest possible sum to the largest.
From 3 + 6 + 9 = 18, to 36 + 39 + 42 = 117.
This is from the 6th multiple of 3, to the 39th multiple of 3.
6 - 5 = 1, 39 - 5 = 34
There are 34 distinct sums.
