Then S=4x+20.
S = 8 * (x- 1)+n (n < 8, n is a positive integer) (S x is a positive integer).
Find x=7-(n/4)? It can be inferred from the meaning of the question that n=4? x=6
That is, six people plant trees, a total of 44 classes?
24: set with x? Pair with B y
∴x+y=60
80x+50y≤4200
40x+70y≤3090
The figure shows that the integer points between point A and point B all meet the requirements.
The coordinates of point A are (37,23), and the coordinates of point B are (40,20).
So there are four schemes, namely (37, 23)(38, 22)(39, 2 1)(40, 20).
(2) Because A+B=60? A is cheaper, so to make the total cost cheaper, we must use the scheme with the most A. That is, A=40 B=20.
At this time, the total cost m = 40 *1000+20 *1500 = 70000.