If she were to add 5 nickels ($0.25), then she would have an equal number of nickels and quarters, and her total would be $5.10. An equal number of nickels and quarters gives a multiple of $0.30. $5.10 is 17 times $0.30. The number of quarters Kendra has must be 17, but she has 5 fewer nickels, so
Kendra has 17 quarters and 12 nickels.