So s = (50-x) (60-2x) = 2x2-160x+3000.

So the answer is: 2x2-160x+3000;

(2) From the meaning of the question: 50× 60-(2x2-160x+3000) =-2x2+160x =1041000× 50× 60,

Solve? x 1=2，x2=78。 ?

And 0 < x < 50, so x=2,

A: The width of the tunnel is 2 meters.