3. (3 points) If two natural numbers are divided, the quotient is 4, and the remainder is 3; the sum of the dividend, divisor, quotient, and remainder is 100. Then the dividend is $\qquad$ .
【Solution】Solution: Let the divisor be $X$, according to the problem, we have:
$$
\begin{aligned}
4 x+3 & =100-x-4-3 \\
5 x & =90, \\
x & =18,
\end{aligned}
$$

That is: The divisor is 18, so the dividend is $100-18-4-3=75$.
Answer: The dividend is 75.
Therefore, the answer is: 75.