Помогите решить (обе буквы), даю 22 балла.

А)
$\frac{17}{4.3 - c} = 5.1 \\ 4.3 - c = 17 \div 5.1 \\ 4.3 - c = 17 \div \frac{51}{10} \\ 4.3 - c = 17 \times \frac{10}{51} \\ 4.3 - c = \frac{10}{3} \\ c = 4.3 - \frac{10}{3} = \frac{43}{10} - \frac{10}{3} = \frac{129}{30} - \frac{100}{30} = \frac{29}{30}$
б)
$\frac{0.4}{c - \frac{3}{4} } = 1 \frac{1}{3} \\ c - \frac{3}{4} = 0.4 \div 1 \frac{1}{3} \\ c - \frac{3}{4} = \frac{4}{10} \div \frac{4}{3} \\ c - \frac{3}{4} = \frac{4}{10} \times \frac{3}{4} \\ c - \frac{3}{4} = \frac{3}{10} \\ c = \frac{3}{10} + \frac{3}{4} = \frac{6}{20} + \frac{15}{20} = \frac{21}{20} = 1 \frac{1}{20}$