the population of a town is 7900 . it decreases annually at the rate of 10 % p . a . what was its population 2 years ago ?
"formula : ( after = 100 denominator ago = 100 numerator ) 7900 ã — 100 / 90 ã — 100 / 90 = 9753 a )"
subtract(subtract(7900, multiply(7900, divide(10, const_100))), multiply(subtract(7900, multiply(7900, divide(10, const_100))), divide(10, const_100)))