3. (8 points) Shuaishuai memorized more than a hundred words in seven days. The number of words he memorized in the first three days was $20 \%$ less than the number of words he memorized in the last four days, and the number of words he memorized in the first four days was $20 \%$ more than the number of words he memorized in the last three days; therefore, Shuaishuai memorized $\qquad$ words in seven days.
【Solution】Solution: According to the analysis, let the number of words memorized in the first three days be $x$, the number of words memorized on the fourth day be $y$, and the number of words memorized in the last three days be $z$, then:
$x=\frac{4}{5}(y+z) ; x+y=\frac{6}{5} z$, solving gives: $9 y=2 z, 5 x=22 y \Rightarrow x: y: z=44: 10: 45$ and $100<x+y+z<200$,

Let $x=44 k$, then $y=10 k, z=45 k$
$$
100<44 k+10 k+45 k<200 \Rightarrow 100<99 k<200
$$

Only when $k=2$, can the condition be satisfied, at this time the total number of words memorized over seven days is: $x+y+z=99 k=99 \times 2=198$ Therefore, the answer is: 198