According to the meaning of the question, you must

{ 4x+2( 10-x)≥30

{ x+2( 10-x)≥ 13

To solve this set of inequalities, you must

5≤x≤7

X is a positive integer.

∴x=5,6,7

∴ 10-x are 5 years old, 4 years old and 3 years old respectively.

A: There are three options, namely, arranging 5 trucks A and 5 trucks B;

6 trucks A and 4 trucks B; There are seven trucks a and three trucks B.

(2) Let the total freight be Y yuan.

According to the meaning of the question, y = 2000x+1300 (10-x).

=700x+ 13000

∵700>0

Y increases with the increase of x

When x=5, y is the smallest.

y = 700 * 5+ 13000 = 3500+ 13000 = 16500

Answer: You should choose the first option, with the lowest freight, the lowest freight 16500 yuan.

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Hehe ~! I also took the senior high school entrance examination this year!

Liaoning!

Come on!

Good luck!