SAT Math Prob

How would I solve this problem? Thank you!!
Let f(x)=1−
1
x
. Which of the following is a possible value of f(x) for x<−1?

A 1/7
B 5/7
C 9/7
D 15/7
E 19/7

Did you mean to type f(x) = 1 - (1/x)?