What is 0.2 of a whole

How do you use the elimination method for this question? explain, because i really want to understand!

Which of the following is true for the relation f(x)=2x^2+1

Someone this asap for a group of students attends a basketball game. * the group buys x hot dogs at the concession stand for $2 each. * the group buys y drinks at the concession stand for $3 each. the group buys 29 items at the concession stand for a total of $70. how many hot dogs did the group buy?