这两道题好象都得用数学思路解决，但我不太明白，麻烦各位帮忙一下，谢谢。
1. A recent survey of all auto accident victims in Dole County Found that, of the severely injured drivers and front-seat passengers, 80 percent were not wearing seat belts at the time of their accidents. This indicates that, by wearing seat belts, drivers and front-seat passengers can greatly reduce their risk of being severely injured if they are in an auto accident.
The conclusion above is not properly drawn unless which of the following is true?
答案：Of all the drivers and front-seat passengers in the survey, more than 20persent were wearing seat belts at the time of their accidents.
2. Figures issued by the government of a certain country show that in 1980 the public sector and the private sector each employed the same number of people. Between 1980 and 1984, according to the government, total employment decreased in the public sector more than it increased in the private sector.
If, according to government figures, the unemployment rate in this country was the same in botn 1980 and 1984, which of the following statements must be true about thid country?
答案：Fewer people were in the labor force, as counted by the government, in 1984 than in 1980.fficeffice" />

1.i am not clever or the answer is wrong
2.for example,in 1980,there are 100 in pulic,and 100 in private,the total laber force is 200 in 1984 there are 80 in Public ,and 110 in private.the total number is 190.so fewer labor force in 1984 than in 1980fficeffice" />