a and b together can do a piece of work in 6 days and a alone can do it in 13 days . in how many days can b alone can do it ?
"explanation : a and b can do work 1 / 6 in 1 day a alone can do 1 / 13 work in 1 day b alone can do ( 1 / 6 - 1 / 13 ) = 7 / 78 work in 1 day = > complete work can be done in 78 / 7 days by b answer : option c"
inverse(subtract(inverse(6), inverse(13)))