the population of a town is 8000 . it decreases annually at the rate of 10 % p . a . what was its population 2 years ago ?
"formula : ( after = 100 denominator ago = 100 numerator ) 8000 ã — 100 / 90 ã — 100 / 90 = 9876 a )"
subtract(subtract(8000, multiply(8000, divide(10, const_100))), multiply(subtract(8000, multiply(8000, divide(10, const_100))), divide(10, const_100)))