Gary has a box of coins that he uses to go to the gas station and get junk food. The box currently contains 53 coins consisting of nickels, dimes, and quarters. The number of quarters is equal to the number of nickels. The total value of
coins is $5.80. What is the sum of quarters and dimes?

Step-by-step explanation:

Givens

According to the problem, if Ryan used 72 milliliters in 6 days, that means he used per day:

If we call days, and the amount of plant food remaining, the expression that models this situation is

Where the constant ratio of change is 12, and it's negative, because the plant food is decreasing.

Notice that we use a linear function to model the situation, because the problem speficies that the plant food decreases an equal amount each day, which refers to the constant ratio of change, which is a linear ratio.