Acoin collector bought a set of coins for $500, and then sold the set for $850, making a profit of $50 per coin. how many coins were in the set?

For this case, the first thing we must do is calculate the total profit.

We have then:

Then, we look for the number of coins.

For this, we need the total profit (which we already calculate) and the amount of profit per coin.

We have then:

The amount of coins that was on the set is:

hey! so 1 (25) out of 4 (100) is 25 so your answer is 25%. it's like quarters!