Solving for an Unknown Practice Test

A streaming service charges $12 each month plus a $5 one-time fee. After a few months, the total cost is $53. Let $x$ be the number of months paid for. This situation is represented by $12x + 5 = 53$. If $12x + 5 = 53$, what is $x$?

Maya buys 3 notebooks and 1 binder, and the total is $18. The binder costs $6. The notebooks all cost the same amount, and sales tax is already included. The situation can be modeled by $3x + 6 = 18$, where $x$ is the price of one notebook. If $3x + 6 = 18$, what is $x$?