Answer: a) Number of nickels, dimes, and quarters are 80, 120, 300 respectively.
b) The coins are worth of 91 dollars i.e. $91 in the piggy bank.
Explanation:
Since we have given that
For every 2 nickels there are 3 dimes ,
So, their ratio will be 2:3
and for every 2 dimes there are 5 quarters.\,
So, their ratio will be 2:5
Now, we'll first find the ratio of nickles to dimes to quarters i.e.
Nickle Dimes Quarters
2 3
2 5
So, it becomes ,
Nickle : Dimes : Quarters
2×2 : 3×2 : 3×5
4 : 6 : 15
Now, let the number of nickle be 4x
Let the number of dimes be 6x
Let the number of quarters be 15x
According to question,

So, number of nickels is given by

Number of dimes is given by

Number of quarters is given by

As we know that

So, According to our question, we get

Hence,
a) Number of nickels, dimes, and quarters are 80, 120, 300 respectively.
b) the coins are worth of 91 dollars i.e. $91 in the piggy bank.