Joan's stamp collection consists of three books. Two tenths of her stamps are on the first book, several sevenths are in the second, and there are 303 stamps in the third book. How many stamps are there in Joan's collection?

Answer 1

"several" sevenths? What kind of nonsense is that?

Anyway if that means 5/7, then
2/10 + 5n/7 + 303 = n
n = 3535

Answer 2

make that 2n/10 + 5n/7 + 303 = n

Answer 3

The answer is 3535. Let x = total books, y = several sevenths. The equation to solve is 2x/10 +xy/7 +303=x. Getting rid of the denominators by multiplying both sides by 35 and collecting the unknowns on one side you have 7x + 5xy-35x = -35(303). y can only be one of the following: 2,3,4,5,6,7 (since the problem says "several sevenths" you can eliminate 0,1). By process of elimination y=5 works and x=3535