You have a total of 21 coins that are nickels and quarters. The coins have a value of $2.25. How many quarters do you have?

Answer: 6

Step-by-step explanation:

Let n represent the quantity of nickels and q represent the quantity of quarters, then set up a system of equations and solve for q.

Quantity: n + q = 21 → - 5 (n + q = 21) → - 5n - 5q = - 105

Value: 5n + 25q = 225 → 1 (5n + 25q = 225) → 5n + 25q = 225

20q = 120

q = 6