Don't know this please help me

On an airplane there are two seats on the left side and three seats on the right side there are 90 seats o the right side of the plane

Write the expression in simplified radical form. show all steps and work including any foil method work. (hint: use the conjugate. no decimal answers.) (9-2√3)/(12+√3)

12. the amount of money in a bank account decreased by 21.5% over the last year. if the amount of money at the beginning of the year is represented by ‘n', write 3 equivalent expressions to represent the amount of money in the bank account after the decrease?