In a 10 gal of an 11% salt solution,
11% of 10 gal are sal.
11% *10 gal=(11/100)*10 gal =0.11*10 gal = 0.1 gal is salt.
Similarly, 0.07*6 gal= 0.42 gal is salt of the 6 gal in the second solution.
The mixture is 10 gal +6 gal = 16 gal, and contains a total of
0.1 gal +0.42 gal = 0.52 gal of salt.
0.52 = x% of 16
0.52=x%*16
x=(0.52/16)*100=0.0325*100=3.25
Answer: there is 0.52 gal of salt in the mixture, that is 3.25%