There are nickels and nickels in the piggy bank every day. It is estimated that there are five or six dollars. He wants to donate all his money to Project Hope. Make it hard every day.

Because it is a multiple of 7 times "the number of coins in the first pile of 2 cents and 5 cents is equal"

Divide these coins into equal amounts of money with "the second pile of 2 cents is equal to 5 cents", and both piles are multiples of 20.

Because it is between 500 and 600, it is 560.

Namely 5.6 yuan.