if a certain toy store ' s revenue in november was 4 / 5 of its revenue in december and its revenue in january was 3 / 4 of its revenue in november , then the store ' s revenue in december was how many times the average ( arithmetic mean ) of its revenues in november and january ?
"let dec rev = 100 then nov rev is 4 / 5 ( 100 ) = > 80 therefore jan rev = 3 / 4 ( nov rev ) = 3 / 4 ( 80 ) = > 60 hence dec rev = x * ( nov rev + jan rev ) / 2 100 = x * ( 80 + 60 ) / 2 x = 100 / 70 = > 1.42 = 2 ans ) d"
divide(3, divide(add(divide(4, 5), multiply(divide(4, 5), divide(3, 4))), const_2))