Question

Explain how to solve this using 2 equations in 2 unknowns. Compare and contrast these 2 methods. A coin bank contains only nickels and dimes. The total value of the coins in the bank is $2.50. The number of nickels is 3 times the number of dimes. How many dimes are there

Answer 1

Answer: the coin bank has 30 nickels and 10 dimes.

Explanation:

The worth of a dime is 10 cents. Converting to dollars, it becomes

10/100 = $0.1

The worth of a nickel is 5 cents. Converting to dollars, it becomes

5/100 = $0.05

Let x represent the number of nickels in the coin bank.

Let y represent the number of dimes in the coin bank.

A coin bank contains only nickels and dimes. The total value of the coins in the bank is $2.50. This means that

0.05x + 0.1y = 2.50 - - - - - - - - - - - 1

The number of nickels is 3 times the number of dimes. This means that

x = 3y

Substituting x = 3y into equation 1, it becomes

0.05 × 3y + 0.1y = 2.50

0.15y + 0.1y = 2.5

0.25y = 2.5

y = 2.5/0.25 = 10

x = 3y = 3 × 10

x = 30