Six beavers are able to build a dam in 6 days. When they worked for 2 days, it turned

Six beavers are able to build a dam in 6 days. When they worked for 2 days, it turned out that due to an impending flood, they had to finish work a day earlier than planned. How many beavers do they need to call for help?

In 1 day, 6 beavers will build 1/6 of the dam.
In 2 days, 6 beavers will build 2 * 1/6 = 1/3 of the dam.
It remains to build 2/3 of the dam in 4 days, or 1/6 of the dam every day.
But, since the work must be completed a day earlier, then 2/3 of the part must be completed in 3 days, or for each day it is necessary to build (2/3) / 3 = 2/9 of the part of the dam.
Let’s make the proportion:
1/6 part is built by 6 beavers;
2/9 pieces build x beavers.
X = (2/9 * 6) / (1/6) = 2 * 36/9 = 2 * 4 = 8 beavers.
Thus, another 8 – 6 = 2 beavers should come to the rescue.