some persons can do a piece of work in 12 days . two times the number of such persons will do half of that work in
"explanation : let x men can do the in 12 days and the required number of days be z more men , less days [ indirect proportion ] less work , less days [ direct proportion ] answer : d ) 3 days"
multiply(multiply(12, divide(const_1, const_2)), divide(const_1, const_2))