3. A brigade of tractor drivers needs to plow two fields, such that the area of one field is twice as large as the area of the other field. On the first day, all the tractor drivers plowed the first field. On the second day, half of the brigade completed the plowing of the first (larger) field, while the other half of the brigade plowed the second field. The second half of the brigade could not finish plowing the second field in one day, so one tractor driver had to plow for two more days to complete it. How many tractor drivers were in the brigade? (It is assumed that all tractor drivers work under the same conditions and have the same productivity.)
Solution. Let there be $x$ tractor drivers in the brigade. From the conditions of the problem, it follows that for plowing the first field, $x+\frac{x}{2}$ workdays of one tractor driver are needed, and for plowing the second field, $\frac{x}{2}+2$ workdays of one tractor driver are needed. Now, since the first field is twice as large as the second field, we get

$$
x+\frac{x}{2}=2\left(\frac{x}{2}+2\right)
$$

from which we find $x=8$. Therefore, the brigade consisted of 8 tractor drivers.