Помогите решить все кроме четвертых заданий

Question 1

Question 2

Вариант 3:
$1)a) \frac{1}{5} + \frac{2}{5} + \frac{4}{15} = \frac{3}{15} + \frac{6}{15} + \frac{4}{15} = \frac{13}{15} \\ b) \frac{1}{3} + \frac{1}{4} + \frac{1}{6} = \frac{4}{12} + \frac{3}{12} + \frac{2}{12} = \frac{9}{12} = \frac{3}{4} \\ 2)a)1 - \frac{2}{5} - \frac{3}{5} = \frac{5}{5} - \frac{2}{5} - \frac{3}{5} = 0 \\ b) \frac{4}{9} - \frac{1}{18} = \frac{8}{18} - \frac{1}{18} = \frac{7}{18} \\ 3)a) \frac{18}{13} - \frac{x}{13} = 1 \\ \frac{18 - x}{13} = 1 \\ 18 - x = 1 \times 13 \\ 18 - x = 13 \\ x = 18 - 13 \\ x = 5 \\ b) \frac{5}{8} + \frac{x}{8} = 1 \\ \frac{5 + x}{8} = 1 \\ 5 + x = 1 \times 8 \\ 5 + x = 8 \\ x = 8 - 5 \\ x = 3$
Вариант 4:

$1) a)\frac{1}{6} + \frac{5}{6} + 3 \frac{1}{10} = \frac{6}{6} + 3.1 = 1 + 3.1 = 4.1 \\ b) \frac{1}{2} + \frac{1}{4} + \frac{1}{8} = \frac{4}{8} + \frac{2}{8} + \frac{1}{8} = \frac{7}{8} \\ 2)a)1 - \frac{1}{5} - \frac{2}{5} = \frac{5}{5} - \frac{1}{5} - \frac{2}{5} = \frac{2}{5} = 0.4 \\ b) \frac{3}{8} - \frac{1}{16} = \frac{6}{16} - \frac{1}{16} = \frac{5}{16} \\ 3)a) \frac{25}{17} - \frac{x}{17} = 1 \\ \frac{25 - x}{17} = 1 \\ 25 - x = 1 \times 17 \\ 25 - x = 17 \\ x = 25 - 17 \\ x = 8 \\ b) \frac{3 }{7} + \frac{x}{7} = 1 \\ \frac{3 + x}{7} = 1 \\ 3 + x = 1 \times 7 \\ 3 + x = 7 \\ x = 7 - 3 \\ x = 4$