Răspuns :

 

[tex]\displaystyle\bf\\\frac{x}{y}=\frac{5}{7}\\\\a)\\\\\frac{x+y}{y}=\frac{x}{y}+\frac{y}{y}=\frac{5}{7}+1=1\frac{5}{7}=\frac{1\times7+5}{7}=\frac{12}{7}\\\\b)\\\\\frac{2x+y}{2y}=\frac{2x}{2y}+\frac{y}{2y}=\frac{5}{7}+\frac{1}{2}=\frac{10}{14}+\frac{7}{14}=\frac{10+7}{14}=\frac{17}{14}\\\\c)\\\frac{5x+3y}{4y}=\frac{5x}{4y}+\frac{3y}{4y}=\frac{5}{4}\times\frac{5}{7}+\frac{3}{4}=\frac{5\times5}{4\times7}+\frac{3}{4}=\\\\=\frac{25}{28}+\frac{3}{4}=\frac{25}{28}+\frac{21}{28}=\frac{25+21}{28}=\frac{46}{28}[/tex]

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[tex]\displaystyle\bf\\d)\\\\\frac{4x-y}{y}=\frac{4x}{y}-\frac{y}{y}=4\times\frac{5}{7}-1=\frac{4\times5}{7}-\frac{7}{7} =\frac{20}{7}-\frac{7}{7}=\frac{20-7}{7}=\frac{13}{7}[/tex]