少了一个关键的单词哟,
If two typists can type two pages in five minutes ,how many typists will it take to type twenty pages in ten minutes
A 10
If two typists type 2 pages in 5 minutes
In 1 minute they will type 2/5pages
therefore 2 typists type 2/5 pages in 1 minute
1 typist will type (2/5)/2 pages in 1 minute(he will type less)=1/5 pages.eqn 1
x typists type 20 pages in 10 minutes
in 1 minute they will type 20/10 pages=2 pages
therefore x typists type 2 pages in 1 minute
1 typist will type 2/x pages.eqn 2
equating eqn 1 and 2 gives 2/x=1/5
therefore x =10 typists