According to the meaning of the question, you must
solve
.
A: Every skilled worker and new worker can install four or two electric cars every month.
(2) Set up a factory with skilled workers.
According to the meaning of the question, it is 12(4a+2n)=240.
2a+n= 10，
n= 10-2a，
A and n are positive integers, 0 < n < 10,
So n=8, 6, 4, 2.
That is, the factory has four recruitment schemes for new workers.
(3) Combining with (2), it is known that the number of new workers should be more than skilled workers, n=8, a =1; Or n=6 and a = 2；; Or n=4 and a = 3.
According to the meaning of the question, you must
w = 2000 a+ 1200n = 2000 a+ 1200( 10-2a)= 12000-400 a。
To make the total monthly salary of the factory W (yuan) as little as possible, A should be the largest.
Obviously, when n=4 and a=3, the less the total monthly salary of the factory, the better.