Question

Suppose you have 20 coins that total $3.00. Some coins are nickels and 1 point

some are quarters. Which of the following pairs of equations can you use to
find how many of each coin you have?

Answer 1

n + q = 20

5n + 25q = 300 or 0.05n + 0.25q = 3

Explanation:

You know that you have some nickels and some quarters, and together there are 20 coins. So if n represents the number of nickels, and q represents the number of quarters, you can use this equation:

n + q = 20

You also know that together the coins total three dollars. We know that a nickel is worth 5 cents and a quarter is worth 25. So if n and q still represent the number of each type of coin, we can use this equation:

5n + 25q = 300

or

0.05n + 0.25q = 3

The reason I said 300 in the first equation is because you are counting the number of cents. There are 300 cents in 3 dollars.