in this network of pipe , the author make the attempts to solve it using ( Q1 = Q2 + Q3) , so delta Q = Q1 -(Q2 +Q3) , the value of head of junction that he gt is 25.2 , with delta Q = (3x10^-3) ( not shown in the working)

however, when i tried to solve it using ( Q1 + Q2 = Q3) , which means ( Q1 +Q2 - Q3 ) , thae ans that i gt is hj = 28 , with delta Q = 0.07

P/s : we have to find the delta Q = 0 for the ans so that water from inlet = water from outlet

so , question has two ans depending on the flow of water ??? or i am wrong ?

http://i.imgur.com/6flQiEl.png http://i.imgur.com/HgmiqYg.png http://i.imgur.com/1vOdsVC.png http://i.imgur.com/5TQE3AW.png http://i.imgur.com/tLVwDXk.png