№12. Решите уравнения: 7 12 4 a)x+] = -x-300+ 5 6 6)25-3,5y = 8,2y-13,61; C)

a) \(\frac{7}{12}x + \frac{4}{9} = - \frac{1}{4}x - 5 \frac{5}{6} + 10.9\)
\(\frac{7}{12}x + \frac{1}{4}x = - \frac{1}{4}x - \frac{35}{6} + \frac{109}{10} - \frac{4}{9}\)
\(\frac{7}{12}x + \frac{1}{4}x = \frac{-35 \cdot 15 + 109 \cdot 9 - 4 \cdot 20}{90}\)
\(\frac{7}{12}x + \frac{1}{4}x = \frac{-525 + 981 - 80}{90}\)
\(\frac{7}{12}x + \frac{1}{4}x = \frac{376}{90}\)
\(\frac{7}{12}x + \frac{1}{4}x = \frac{188}{45}\)
\(\frac{7 \cdot 3 + 1 \cdot 3}{36}x = \frac{188}{45}\)
\(\frac{21 + 3}{36}x = \frac{188}{45}\)
\(\frac{24}{36}x = \frac{188}{45}\)
\(\frac{2}{3}x = \frac{188}{45}\)
x = \(\frac{188}{45} \cdot \frac{3}{2}\)
x = \(\frac{94}{15} \cdot \frac{1}{1}\)
x = \(\frac{94}{15}\)

б) 25 - 3.5y = 8.2y - 13.61
-3.5y - 8.2y = -13.61 - 25
-11.7y = -38.61
y = \(\frac{-38.61}{-11.7}\)
y = 3.3