[tex]a. \frac{1}{2} = \frac{n}{4} = > n = \frac{4}{2} = 2[/tex]
[tex]b. \frac{6}{n } = \frac{18}{16} = > n = \frac{6 \times 16}{18} = 5.(3)[/tex]
[tex]c. \frac{n + 1}{22} = \frac{2n}{40} = \frac{n}{20} = > \\ 20(n + 1) = 22n \\ 20n + 20 = 22n \\ 20 = 22n - 20n [/tex]
2n=20
n=10