Answer: 10 nickels
Explanation:
A pennie is a cent or $0.01. Serenity has 12 pennies so the amount she has from pennies is:
= 12 * 0.01
= $0.12
The amount she has in nickels at most is therefore:
= 0.66 - 0.12
= $0.54
A nickel is $0.05 so the number of nickels are:
= 0.54/0.05
= 10.8 nickels
= 10 nickels
If she has 10 nickels then the total she would have is:
= (12 * 0.01) + (10 * 0.05)
= $0.62
This fits the parameters