Set x hectares of green vegetables, y hectares of cucumbers and 10-x-y hectares of tomatoes.

Need labor:

2.5x+5y+3.75( 10-x-y)= 37.5- 1.25 x+ 1.25y = 40

That is 1.25y- 1.25x=2.5.

y=2+x

Output value:

12x+22.5y+ 18( 10-x-y)= 180-6x+4.5y

That is180-6x+4.5y.

= 180-6×4.5(2+x)

= 189- 1.5x

Because x≥2

So when x=2, the maximum output value is189-1.5 * 2 =186,000 yuan.

Y=4， 10-x-y=4。

that is

2 hectares of green vegetables, 5 laborers.

Cucumber 4 hectares, 20 laborers.

4 hectares of tomatoes, 15 labor.

Maximum output value186,000 yuan.