Răspuns:
[tex] = ( \frac{a}{c} - 10 - b - 10+ d) \times \frac{1}{2} - \frac{1}{10} \\ = ( \frac{a}{c} - 20 - b + d) \times \frac{1}{2} - \frac{1}{10} \\ = \frac{a - 20c - bc + cd}{c} \times \frac{1}{2} - \frac{1}{10} \\ = \frac{a - 20c - bc + cd}{2c} - \frac{1}{10} \\ = \frac{5(a - 20c - bc - cd) - c}{10c} \\ = \frac{5a - 100c - 5bc + 5cd - c}{10c} \\ = \frac{5a - 101c - 5bc + 5cd}{10c} [/tex]