Răspuns:
x=62
Explicație pas cu pas:
Folosim formula:
[tex]\displaystyle\boxed{\frac{x}{y} -\frac{z}{y} =\frac{x-z}{y}}[/tex]
[tex]\displaystyle\frac{57}{31} -\frac{16}{31} =\frac{x-21}{31} \\\\\\ \frac{57-16}{31} =\frac{x-21}{31}[/tex]
[tex]\displaystyle\frac{41}{31} =\frac{x-21}{31}[/tex]
In aceasta faza aplicam urmatoarea egalitate
[tex]\displaystyle\frac{x}{y} =\frac{z}{t} daca \ x\times t = y\times z[/tex]
[tex]\displaystyle\frac{41}{31} =\frac{x-21}{31}[/tex]
[tex]\displaystyle 41\times 31= 31\times (x -21 )\\\\ 41=x-21\\ \\ x=41+21\\ \\ x=62[/tex]
