Which sentence of the explanation do you not understand?
The ratio 6 : 2 is the same as 3 : 1. The latter ratio means that for every three wins, there is one loss. How many groups of three wins are in nine wins? By definition of division, this is 9 / 3 = 3 groups of three. Therefore, there are three losses.
Since above the divisor and the quotient are both 3, let me give another example. If there were 12 wins initially and the ratio were still 3 : 1, how many groups of 3 wins are in 12 wins? It's 12 / 3 = 4 groups. For each group (of 3 wins), there is a single loss. Therefore, there are 4 losses. This example is not related to the problem in post #1.