Answer:she had $35 at the beginning
Explanation:
Let x represent the total amount of money that Ellen had initially.
Ellen uses 2/7 of her money to pay for a book. This means that the amount that Ellen spent on books would be 2/7 × x = 2x/7
The remaining amount would be
x - 2x/7 = 5x/7
She uses 2/5 of the remaining money to pay for a bag. This means that the amount paid for the bag would be
2/5 × 5x/7 = 2x/7
The amount that she has left would be 5x/7 - 2x/7 = 3x/7
Ellen has $15 left. Therefore,
3x/7 = 15
3x = 7 × 15 = 105
x = 35