Răspuns:
[tex]e)9 \times (3 + 4 \times (15 + 6 \times a) \div 18) = 81 \\ 9 \times (3 + 60 + 24a \div 18) = 18 \\ 9 \times (63 + \frac{24a}{18} ) = 81 \\ 9 \times (63 + \frac{4a}{3} ) = 81 \\ 9 \times 63 + 9 \times \frac{4a}{3} = 81 \\ 567 + 12a = 81 \\ 12a = 81 - 567 \\ 12a = - 486 \\ a = - \frac{486}{12} \\ a = - \frac{81}{2} [/tex]
[tex]((a \div 3 - 1) \div 6 + 489) \div 25 + 2 = 26 \\ (( \frac{a}{3} - 1) \div 6 + 489) \div 25 + 2 = 26 \\ ( \frac{a}{3} \times \frac{1}{6} - \frac{1}{6} + 48) \div 25 + 2 = 26 \\ ( \frac{a}{18} - \frac{1}{6} + 48) \div 25 + 2 = 26 \\ ( \frac{a}{18} - \frac{3}{18} + \frac{864}{18} ) \div 25 + 2 = 26 \\ \frac{a + 861}{18} \div 25 + 2 = 26 \\ \frac{a + 861}{18} \times \frac{1}{25} = 26 \\ \frac{a + 861}{450} = 26 \\ a + 861 = 450 \times 26 \\ a + 861 = 11700 \\ a = 11700 - 861 \\ a = 10839[/tex]
