Solve it and get: x=50, so it is practical? 50× (1+20%) = 60 tons
(2) Solution: If there are Y Type A cars, there are (16-y) Type B cars, which are derived from the meaning in the question:
20y+ 15( 16-y)≥300
500y+300( 16-y)≤7800
To solve this problem, you must:
12≤y≤ 15
And y is an integer.
Y can be 12, 13, 14, 15.
There are four schemes.
① 12 A car? Four b-cars?
② 13 A car? Three b-cars.
314 a car? Two b-cars.
415 a car? 1 B car
(3) Solution: Let w be the total transportation cost, then:
w=500y+300( 16-y)
That is w=200y+4800.
The smaller y, the lower the cost.
∴y takes 12 as the minimum value.
In other words, the cost of the first scheme is lower.