Ben earns $12,800 a year. About 15% is taken out for taxes. How much is taken out for taxes?

Which of the following expressions are equivalent ?

Asocial networking site currently has 400,000 active members, and that figure is predicted to increase by 32% each year. the following expression represents the number of active members on the site after t years.

For what values of the variable x is the expression square root of 7x+14+ square root of 7-x a real number?