【Analysis and Solution】Proportion Application Problem

Let the number of people arranged to produce parts A, B, and C be $x$ people, $y$ people, and $z$ people, respectively, so that the parts produced per hour can be perfectly matched; then $30 x: 25 y: 20 z=3: 5: 4$; thus $x: y: z=\frac{3}{30}: \frac{5}{25}: \frac{4}{20}=\frac{1}{10}: \frac{1}{5}: \frac{1}{5}=1: 2: 2$;

There are a total of 45 workers; therefore, arranging 9 people to produce part A, 18 people to produce part B, and 18 people to produce part C will ensure that the parts produced per hour can be perfectly matched.
【Question 12】
There are 45 workers. If each person can produce 30 part A per hour, or 25 part B per hour, or 20 part C per hour. Now, 3 part A, 5 part B, and 4 part C are used to assemble a certain machine. Therefore, the number of people assigned to produce part A, part B, and part C should be $\qquad$ people, $\qquad$
$\qquad$ people, respectively, so that the parts produced per hour can be perfectly matched.