Any one helpful enough to solve this properly

What is the first step of an indirect proof of a number that is divisible by two

[10 points, algebra 2-simplifying complex fractions]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Jason went to an arcade to play video games. he paid $2 for every 11 tokens he bought. he spent a total of $16 on tokens. which equation can be used to determine, t, the number lf tokens jason bought