Question

A crate contains 300 coins and stamps. The coins cost $3 each and the stamps cost $1.5 each. The total value of the items is $825. How many coins are there?

Answer 1

Let the number of stamps be s and the number of coins be c.

This means that s+c=300 and 3c+1.5s=825.

Multiplying the first equation by 3 yields 3s+3c=900.

Subtracting the second equation from this gives that 1.5s=75, and thus s=50.

It follows that c=250, so there are 250 coins.