3. (8 points) In a cage, there are 30 crickets and 30 grasshoppers. The Red-Haired Magician, with each transformation, turns 4 grasshoppers into 1 cricket; the Green-Haired Magician, with each transformation, turns 5 crickets into 2 grasshoppers. After the two magicians have transformed a total of 18 times, there are only grasshoppers left in the cage, with no crickets. At this point, there are $\qquad$ grasshoppers.
3. (8 points) In a cage, there are 30 crickets and 30 grasshoppers. The Red-Haired Magician, with each transformation, turns 4 grasshoppers into 1 cricket; the Green-Haired Magician, with each transformation, turns 5 crickets into 2 grasshoppers. After the two magicians have performed a total of 18 transformations, there are only grasshoppers left in the cage. At this point, there are $\qquad$ grasshoppers.

【Solution】Solution: Regardless of whether it is the Red-Haired Magician or the Green-Haired Magician, each operation reduces the number of animals by 3, so there are:
$$
\begin{array}{l}
60-18 \times 3, \\
=60-54, \\
=6 \text { (animals); }
\end{array}
$$

Answer: At this point, there are 6 grasshoppers.
Therefore, the answer is: 6.