1, 29 can be considered as arithmetic progression, 429-371= 58; 5 16-429=87; 87-58=29. Note that 58 and 87 are multiples of 29, otherwise there is no solution to this problem.

2. 1.6, according to the requirements of the topic, one trip takes 45 minutes, and the whole journey takes 165 minutes. If the last trip does not rest, it can be considered as165+15 =180. Because the backwater speed is not considered first, you can run in four stages at most.

3,46, assuming continuous addition to n, then (1+n) * n/2.

4,42, find the least common multiple of 7/3/2,42.

5, 450, time can be equivalent to the length (it is best to write the formula clearly). If the train length is L, you can get 300+2L:L=8:3, L = 450.

6,4,: 1, and divide the salt itself into150:150;

.2,30: 5+25 (salt), and the salt content is 150,125,25;

3.30+ 100 (salt): 5+ 125 (salt), and salt is divided into 100,50, 125,25;

4. 100: 100, divided into three piles 100.

Is there anything faster? Please think about it together.

7、7.5; Cart speed x, cart speed y, (2+5) x = 5y; (2+3)x=3(y+5) gives y=7.5.

8、 1350; A cost x, b cost y; Then x+y = 2200; You can get (1.2× 0.9-1) x+(1.15× 0.9-1) y =131,x.

I went to bed before I finished.