[tex] \frac{17}{18} - \frac{2}{3} [/tex]
You must have a common denominator to subtract
Multiply [tex] \frac{2}{3} by \frac{6}{6} = \frac{12}{18} [/tex]
[tex] \frac{17}{18} - \frac{12}{18} = \frac{5}{18} [/tex]
[tex] \frac{5}{18} [/tex] is your answer