Answer:
There are 63 nickels that Marianna have in her piggy bank.
Step-by-step explanation:
Let us assume that there are x nickels and y quarters in the bank.
Therefore, 0.05x + 0.25y = 9.15 ...... (1)
⇒ x + 5y = 183 ........ (2) {Multiplying both sides with 20}
Now, 90 nickels weighs 1 pound.
Then, x nickels weighs
pounds
Again, 80 quarters weighs 1 pound .
Then, y quarters weighs
pounds.
Given that,
........ (3)
⇒ x + 1.125y = 90 ......... (4) {Multiplying both sides with 90}
Now, subtracting equation (4) from equation (2) we get,
3.875y = 93
⇒ y = 24.
Now, from equation (4) we get, x = 90 - 1.125 (24) = 63.
So, there are 63 nickels that Marianna has in her piggy bank. (Answer)