5x+ 12=y

8x>y

The solution is 8x > 5x+ 12.

x>4

Y 0, x is a positive number

(3/2) m-2 < 0 m < 4/3, y is negative.

Therefore, the range of m

3. (1) y = 25x+15 (10-x), which is simplified as y= 150+ 10x.

(2) 180≤y≤200 and x≥4 is known.

180≤ 150+ 10x≦200

Solution: 3≤x≤5

Therefore, x=4 or x=5 can be obtained.

When x=4, y= 190.

When x=5, y=200.

Therefore, when choosing four buses, the fare is the least.