... either 0, 1, 2 or 3 of the 50¢ stamps. Each of the 5 choices for stamps. This gives a total of 20¢ combinations. However, this total includes the combination of zero 30¢ stamps and zero 50¢ stamps. ... each. Therefore, 19 different amounts of postage can be made. Method 1:Arrange the numbers like this: 1 + 25 = 252 + 23 = 253 + 22 = 25•••12 + 13 = 2525 = 25Method 2:Given (1) S = 1 +...