Is this a function or no?

What is the most accurate measurement of 1 pound

James is playing his favorite game at the arcade. after playing the game 3 times, he has 8 tokens remaining. he initially had 20 tokens, and the game costs the same number of tokens each time. the number tt of tokens james has is a function of gg, the number of games he plays

The sum of two numbers is 86, and their difference is 20. find the two numbers