a is twice as good as b . and together they finish a piece of work in 20 days . in how many days will a alone finish the work
"( a ' s 1 day work ) : ( b ' s 1 day work ) = 2 : 1 a + b 1 day work = 1 / 20 a ' s 1 day work = ( 1 / 20 ) * ( 2 / 3 ) = 1 / 30 a alone can finish the work in 30 days answer is a"
inverse(multiply(divide(inverse(20), add(const_2, const_1)), const_2))