[tex]a = 7\\a' = 4\\b = 8\\\\k = \frac{a}{a'}\\\\k = \frac{7}{4}[/tex]
[tex]\frac{7}{4}x = 8 \ \ |\cdot\frac{4}{7}\\\\x = \frac{32}{7} = 4\frac{4}{7}[/tex]
