\[\boxed{\text{1120.\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\]
\[f(x) = - 1,5x + 6\]
\[0 \leq - 1,5x + 6 \leq 3\]
\[- 6 \leq - 1,5x \leq - 3\]
\[2 \leq x \leq 4.\]