Answer:
number of pennies = 19
number of dimes = 19
number of quarters = 45 - 2 × 19 = 45 - 38 = 7
Step-by-step explanation:
The total number of coins in the box is 45 . The coins consist of pennies, dimes and quarters.
The number of pennies is equal to the number of dimes. The remaining number is the quarters. Therefore,
number of pennies = a
number of dimes = a
number of dimes = 45 - 2a
1 dime = 0.1 dollars
1 penny = 0.01 dollars
1 quarters = 0.25 dollars
Thee total cost can be expressed as follows
3.84 = a(0.01) + a(0.1) + 0.25(45 - 2a)
3.84 = 0.01a + 0.1a + 11.25 - 0.5 a
3.84 = -0.39 a + 11.25
3.84 - 11.25 = -0.39 a
-7.41 = -0.39 a
divide both sides by -0.39
a = -7.41/-0.39
a = 19
number of pennies = 19
number of dimes = 19
number of quarters = 45 - 2 × 19 = 45 - 38 = 7
