Question

Raju & tom together can do a work in 10 days.Tom & appu together can do it in 12 days.Appu & raju together can do it in 15 days.In how many days will they finish it if all the three work together??

Answer 1

let Raju be X, Tom be y and appu be z
then given in qstn that x+y=10....(1)
y+z=12....(2)
z+x=15....(3)
solving 1 and 2 we get x-z=-2....(4)
solving 3 and 4 we get x=13/2
substitute X in eqn 1 we get y=7/2
substitute x in eqn 3 we get z=17/2
so then therefore x+y+z=37/2
approximately 19 days