I want to prepare to do wholesale vegetables, the first: in the morning vegetable farmers there to collect, I want to ask for advice, every day and vegetable farmers to collect the price of vegetables is based on what situation factors to set the price of vegetables? Solution: set a kind of truck each transport x tons, B kind of truck each transport y tons; then the first A kind of truck transported 4x tons, B kind of truck transported 5y tons; the second A kind of truck transported 3x tons, B kind of truck transported 6y tons; according to the meaning of the question, there is a system of equations:

4x + 5y = 28.5

3x + 6y = 27

Solve the system of equations, get: x =4, y=2.5

This batch of vegetables*** has: 5×4+2×2.5=25(tons)

If you pay $20 per ton for shipping, the farmer should pay $25×20=500(yuan)