he had 5 more nickels then he originally thought...so he had 25 cents more then he thought he had......so if he had 4.35......he thought he had 4.35 - 0.25 = 4.10......which is 4.10 / 0.05 = 82 nickels
or this way....
4.35 / 0.05 = 87 nickels....what he had
and if he had 5 more nickels then he thought he had...then he thought he had 87 - 5 = 82 nickels