The school has 90 teachers, of which 66 teachers like drinking tea, and 42 teachers like drinking coffee, and the number of teachers who like both drinks is exactly 3 times the number of teachers who do not like either drink. Then the school has $\qquad$ teachers who like at least one of the two drinks, tea or coffee.
I analysis and solution】Principle of Inclusion-Exclusion. Let the number of people who do not like either of the two drinks be $x$; then the number of people who like both drinks is $3 x$;
$$
(66+42-3 x)+x=90 \text { ; }
$$

Solving for $x=9$;
The number of people who do not like either drink is 9;
Thus, the number of people who like both drinks is $3 \times 9=27$;
The school has $66+42-27=81$ or $100-9=81$ teachers who like at least one of tea or coffee.