Answer: the coin bank has 30 nickels and 10 dimes.
Step-by-step 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
