According to the meaning, 30X= 1 100+400.

The solution is x = 50m/s.

Set up a general factory to produce X thousand tents and a branch factory to produce Y thousand tents.

X+Y=9

1.6X+ 1.5Y= 14

The solution is x = 5 and y = 4.

Suppose that X people are assigned to produce bolts and Y people are assigned to produce nuts.

X+Y=24

12X/2= 18Y/3

X= 12，Y= 12。

Let's assume that x people are transferred to place A and y people are transferred to place B.

X+Y=20

27+X=2( 19+Y)

The solution is X= 17.

Y=3

Let the aircraft speed be Xkm/h when there is no wind.

( 17/6)(26+X)=3(X-26)

The solution is x = 9 10 km/h 0 km/h.