Răspuns :
Fie x-nr
[tex]x+\frac{2x}{5} =14\\\\\frac{5x}{5}+\frac{2x}{5} =\frac{70}{5} |*5\\\\5x+2x=70\\\\7x=70\\\\x=\frac{70}{7}\\\\x=10[/tex]
Notam cu X numarul
X+2/5 din X= 14
X+2/5 × X= 14
X+2X /5=14
Amplificam pe X si pe 14 cu 5
5X /5 +2X /5=70/5
5X+2X=70
7X=70
X=70:7
X=10