She has 9 more nickels than she does dimes.
Explanation: 7 quarters is equal to $1.75, and 11 dimes is equal to $1.10. So, adding these two numbers you get $2.85, and to get the amount of money she has ($3.85) you need exactly $1. So, you have to find how many nickels you need in order to get $1, which is 20. Then from there you just subtract the amount of nickels she has from dimes (20-11) and you get your answer, 9.