[tex] \frac{a}{b} = \frac{4}{5} [/tex]
[tex]5a = 4b[/tex]
[tex]a = \frac{4b}{5} [/tex]
[tex]2a + 3b = 46[/tex]
[tex]2 \times \frac{4b}{5} + 3b = 46[/tex]
[tex] \frac{8b}{5} + 3b = 46 \: | \times 5[/tex]
[tex]8b + 15b = 230[/tex]
[tex]23b = 230[/tex]
[tex]b = \frac{230}{23} [/tex]
[tex]b = 10[/tex]
[tex]a = \frac{4b}{5} [/tex]
[tex]a = \frac{4 \times 10}{5} [/tex]
[tex]a = \frac{40}{5} [/tex]
[tex]a = 8[/tex]