[tex] \frac{11}{19} + \frac{7}{19 } - \frac{6}{19} = \frac{12}{19} [/tex]
[tex] \frac{18}{19 } - \frac{6}{19} = \frac{12}{19} [/tex]
[tex] \frac{12}{19} = \frac{12}{19} [/tex]
