Question

a cistern has two inlets A and B which can fill it in 21 minutes and 28 minutes alone and outlet C can empty the full cistern in 14 minutes if all the three cistern pipes are opened together in the empty in how much time will they fill the cistern​

Answer 1

Step-by-step explanation:

PLS MARK AS BRAINLIEST

1min work of A is 1/21

1min work of B is 1/28

1min work of C is 1/14

therefore

1/21 + 1/28 - 1/14=

=1/84

therefore total time is ¹/1/84 i.e. 84mi

PLS MARK AS BRAINLIEST