The formula would be set up as ratios (or fractions). The first ratio is 6:5, which in total is 11. There were 6 yes out of 11, so the fraction = 6/11.
The second fraction has a total of 5918, however you do not know the amount of yes votes, so the variable placeholder will be called "x".
The final formula would be:
6/11 = x/5918
You do cross multiplication and you get:
11x = 35508. You divide both sides, and you get x = 3228.
Because x is the placeholder for the amount of yes votes, and x = 3228, the amount of yes votes is 3228