[tex]\displaystyle a)\left( \frac{7}{9} + \frac{17}{6} \right)- \left( \frac{5}{6} - \frac{1}{18} \right)= \frac{14+51}{18} - \frac{15-1}{18} = \\ \\ = \frac{65}{18} - \frac{14}{18} = \frac{51}{18} = \frac{17}{6} \\ \\ c)\left(4 \frac{7}{9} -1 \frac{1}{2} \right)-\left( \frac{15}{16} - \frac{1}{24} \right)=\left( \frac{43}{9} - \frac{3}{2} \right)- \frac{45-2}{48} = \\ \\ = \frac{86-27}{18} - \frac{43}{48} = \frac{59}{18} - \frac{43}{48} = \frac{472-129}{144} = \frac{343}{144} [/tex]
