Julian and stacey needed 10 liters of water to fill a tank. stacey filled the tank with 3 11/12 liters of water. julian poured 1 2/5 liters less than stacey into the tank. how much more water is still needed to fill the tank?

The amount of water Julian and Stacey needed to fill the tank = 10 liters
Amount of water filled by Stacey individually = 3 11/12 liters
                                                                       = 47/12 liters
It is given in the question that Julian poured 12/5 liters less than Stacey.
Then Amount of water filled by Julian = (47/12) - (12/5) liters
                                                            = (235 - 144)/60
                                                             = 91/60
So Julian filled 91/60 liters of water in the tank.
Amount of water still needed to fill the tank = 10 - [(47/12) - (91/60)]
                                                                     = 10 - [(235 - 91)/60]
                                                                     = 10 - (144/60)
                                                                     = 10 - 12/5
                                                                     = (50 - 12)/5
                                                                     = 38/5
                                                                     = 7 3/5
so 7 3/5 liters of water is still required to fill the tank.

What do you mean by that?