One person can do a certain job in ten minutes, and another person can do the same job in fifteen minutes. how many minutes will they take to do the job together? 4 min 5 min 6 min

In 1995 america online had about 3000000 users over the next decade users are expected to increase from a few million to the tens of millions suppose the number of users increased by 150% by the year 2000 how many users will there be in the year 2000