[tex]\left \{ {{0,2x+0,5y=5,4,} \atop {\frac{1}{2}x-\frac{1}{8}y=2,5. }} \right.[/tex]

[tex]\left \{ {{0,2x+0,5y=5,4} \atop {x=5+\frac{1}{4} y}} \right.[/tex]
[tex]0,2(5+\frac{1} {4} y)+0,5y=5,4[/tex]
[tex]y=8[/tex]

[tex]x=5+\frac{1}{4} *8[/tex]

[tex]x=7[/tex]

[tex](x,y)=(7,8)[/tex]

[tex]\left \{ {{0,2*7+0,5*8=5,4} \atop {\frac{1}{2}*7-\frac{1}{8}*8=2,5 }} \right.[/tex]

[tex]\left \{ {{\frac{27}{5} =\frac{27}{5} } \atop {\frac{5}{2}=\frac{5}{2} }} \right.[/tex]
[tex](x,y)=(7,8)[/tex]
[tex]x=7\\y=8[/tex]