7. (5 points) A box contains many identical but red, yellow, and blue glass balls. Each time two balls are drawn. To ensure that the result of drawing is the same 5 times, at least $\qquad$ draws are needed.
【Answer】Solution: $(3+3) \times 4+1$
$$
\begin{array}{l}
=6 \times 4+1, \\
=25 \text { (times). }
\end{array}
$$

Answer: At least 25 times to draw balls.