Apopulation of rabbits doubles every 4 month, if it starts out with 8, how many will there be in a year

Me what is the value of x? showing work would be appreciated - ! : )

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

What is the value of x in the equation 2(x-4) = 4(2x + 1)?