Solution:
[tex] \frac{13}{16} x - \frac{3}{8} x = \frac{2}{5} + \frac{3}{10} \\ = > \frac{13x - 6x}{16} = \frac{4 + 3}{10} \\ = > \frac{7x}{16} = \frac{7}{10} \\ = > x = \frac{7}{10} \times \frac{16}{7} \\ = > x = \frac{16}{10} \\ = > x = \frac{8}{5} [/tex]
[tex]s = \frac{2x + t}{r} \\ = > rs = 2x + t \\ = > rs - t = 2x \\ x = \frac{rs - t}{2} [/tex]
