Răspuns:
[tex]\frac{5a+8b}{2a+7b} = 1.25[/tex]
Explicație pas cu pas:
[tex] \frac{a}{b} = 0,3 \iff a = 0,3b \iff a = \frac{3b}{10}\\\frac{5a+8b}{2a+7b} = \frac{5\cdot \frac{3b}{10} + 8b}{2\cdot \frac{3b}{10} + 7b} = \frac{\frac{3b}{2}+8b}{\frac{3b}{5} + 7b} = \frac{\frac{3b + 16b}{2}}{\frac{3b + 35b}{5}} = \frac{5\cdot 19\cancel{b}}{2\cdot 38\cancel{b}} = \frac{5}{2}\cdot \frac{19}{38} = \frac{5}{2}\cdot \frac{1}{2} = \frac{5}{4} = \boxed{1.25}[/tex]
