a can do a work in 15 days and b in 20 days . if they work on it together for 2 days , then the fraction of the work that is left is :
"ans is : c a ' s 1 day ' s work = 1 / 15 b ' s 1 day ' s work = 1 / 20 ( a + b ) ' s 1 day ' s work = ( 1 / 15 + 1 / 20 ) = 7 / 60 ( a + b ) ' s 2 day ' s work = ( 7 / 60 * 2 ) = 7 / 30 therefore , remaining work = ( 1 - 7 / 30 ) = 23 / 30 . ans : c"
subtract(const_1, multiply(add(divide(const_1, 15), divide(const_1, 20)), 2))