Let the volumes be 3x, 4x, and 5x
3x=1:4 (Water)3x1+4×1=3x5Alcohol3x1+4×4=12x5
4x=1:3 (Water)4x1+3×1=4x4=xAlcohol4x1+3×3=12x4=3x
5x=2:5 (Water)5x7×2=10x7Alcohol5x7×5=257x
Total water
3x5+x+10x7=21x+35x+50x35=106x35
Total Alcohol
12x5+3x+25x7=84x+105x+125x35=314x35
Overall ratio
=106x35314x35=106314=53157