The rationals being closed under subtraction means that if we start with two rational numbers and subtract them, we get another rational number. Choice c subtracts two rational numbers but gets the wrong answer, so isn't support for anything. Choice b is rational too because the square root of 4 is 2.
Answer: b
The equation would be 14x+2=t......
Breakdown: 14 times X (the number of tickets purchased) plus the one time processing fee of 2 dollars will equal T (the total)
