1。 The unit price is the same, and the amount is proportional to the quantity:12:180 = 30: xx =180 * 30/12 = 450 (yuan).

2. The rice yield is the same, and rice is directly proportional to rice. 200:130 = x: 2600x = 2600 * 200/130 = 4000 kg = 4 tons.

3。 The weight per unit length is the same, and the weight is proportional to the length. 5: 400 = x: 6000x = 6000 * 5/400 = 75m。

4。 . (poor conditions)

5 At the same outlet speed, the outlet water is proportional to the time, 35: 5/7 = x: 1x = 49 (minutes), 49-35= 14 (minutes).

6。 With the same temperature change rate, the temperature difference is directly proportional to the height,100: 0.8 = x: (5-1) x =100 * 4/0.8 = 500m.

Question 4: The same speed and distance are proportional to time.

(1): 210: 3 = 490: xx = 3 * 490/210 = 7 (hours)

(2): 210: 3 = x: 9x = 210 * 9/3 = 630 (km)