请大侠帮我看看这几道题，不是很难

mataoturku

Solution Y is 30 percent liquid X and 70
percent water. If 2 kilograms of water
evaporate from 8 kilograms of solution
Y and 2 kilograms of solution Y are
added to the remaining 6 kilograms of
liquid, what percent of this new solution
is liquid X?

After paying a 10 percent tax on all
income over $3,000, a person had a net
income of $12,000. What was the income
before taxes?

Working alone, R can complete a certain
kind of job in 9 hours. R and S, working
together at their respective rates, can
complete one of these jobs in 6 hours. In
how many hours can S, working alone,
complete one of these jobs?

谢谢