N nickels and 9N dimes.
The "value" equation is
10*(9N) - 5N = 595 cents.
90N - 5N = 595
85N = 595
N = = 7.
ANSWER. 7 nickels and 9*7 = 63 dimes.
CHECK. 63*10 - 7*5 = 595 cents = $5.95. ! Correct !