How to tell whether each function is quadratic

The triangles are similar. what is the value of x? show your work.

Write a story that matches with the expression 42x-5 pls hurry

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?