[tex] \frac{a}{b} = \frac{5}{7} [/tex]
[tex]7a = 5b[/tex]
[tex]a = \frac{5b}{7} [/tex]
[tex] \frac{a + b}{2} = 29.4 \: | \times 2[/tex]
[tex]a + b = 58.8[/tex]
[tex] \frac{5b}{7} + b = 58.8 \: | \times 7[/tex]
[tex]5b + 7b = 411.6[/tex]
[tex]12b = 411.6[/tex]
[tex]b = \frac{411.6}{12} [/tex]
[tex]b = 34.3[/tex]
[tex]a = \frac{5b}{7} [/tex]
[tex]a = \frac{5 \times 34.3}{7} [/tex]
[tex]a = \frac{171.5}{7} [/tex]
[tex]a = 24.5[/tex]
