allow me another way...
we have 1/4 of a sol'' taken away and 3/4 of the sol' remains and lets say as three parts of 1/4 now each 1/4 of the solution has = 10 mg of sugar...
a new sol'' is put and the whole = the three 1/4's and the new 1/4 th all now have 16 mg of sugar... which means that the new 1/4th has 10mg and an extra 6 mg not only that it has more so that each of the three 1/4 ths of the old sol'' to get to have 16 mg of sugar
now putting it clear old 3>. 1/4 th's must have each an extra 6 mg of sugar that is 3*6=18
the new 1/4 th sol' should have another extra 6 mg + the 10 mg= 16
now added up it gets to 34...
I hope that was clear ... in acse of doubt let me know
also the two previous expalnations were fab''
the whole worldmakes way for the man who knows wer he's going... good luck