how many unique positive odd integers less than 90 are equal to the product of a positive multiple of 5 and an odd number ?
"the question basically asks how many positive odd integers less than 90 are odd multiples of 5 so we have 5 , 15,25 , 35,45 , 55,65 , 75,85 = 9 ans b"
divide(divide(90, 5), const_2)