1, a book has * * * 30 pages, one of which has been torn off, and the sum of all the remaining numbers is exactly 450, so which page has been torn off?

1+2+3+。 . . 30=( 1+30)*30/2=465

465-450= 15

15=7+8

So pages 7 and 8 were torn off.

2. Someone bought two commodities and misplaced the decimal point of one of them, and * * * paid the clerk 45.5 yuan. The clerk complained that he should pay for the 68 th hospital. How much are these two things?

Less money: 68-45. 5=22。 5 yuan

Explain that the money of an item has shrunk by 10 times, but it is 22 less. 5 yuan,

Then the original price is 22. 5/(10-1) *10 = 25 yuan.

That is, the price of the other one is: 68-25=43 yuan.