Dad wants one-cent, two-cent, three-cent, five-cent, and ten-cent stamps. He said to get four each of two sorts and three each of the others, but I’ve forgotten which. He gave me exactly enough to buy them; just these dimes. How many stamps of each type does Dad want? A dime is worth ten cents.
Answer
The easy way to solve this is to sell her three each, for 3x(1+2+3+5+10) = 63 cents. Two more stamps must be bought, and they must make seven cents (since 17 is too much), so the fourth stamps are a two and a five.
