When x=12, y=8. Find x when y=12

What is the standard form of -5x^2+2x^4-11+x^3+3x

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.

Tom wants to order tickets online so that he and three of his friends can go to a water park the cost of the tickets is 16.00 per person there is also a 2.50 one-time service fee for ordering tickets online write an expression in term of n that represents the cost for n ordering tickets online