First lets take 96 years.
Number of leap years in 96 years = 96/4 = 24
Now lets take the remaining four years i.e. 97,98,99,100
In these years the year 100 must have been a leap year.but it is not a leap year.
Leap years are those years which can be divisible by 4.So 100 is not divisible by four.Hence there are only 24 leap years
Number of ordinary year = 100 -24 = 76 years