[tex]0.2= \frac{2}{10}= \frac{1}{5} | \\ 0.5= \frac{5}{10}= \frac{1}{2}|=> \left[\begin{array}{ccc}a&b\end{array}\right]---d.p--> \left[\begin{array}{ccc}5&2\end{array}\right] => \frac{a}{5}= \frac{b}{2}=x \\ a-b=12 \\ \\ \frac{a}{5}=x=>a=5x; \frac{b}{2}=x=>b=2x \\ a-b=12<=>5x-2x=12<=> 3x=12=>x=4 \\ x=4 ; a=5x; a=4*5=20 \\ x=4; b=2x=2*4=8 [/tex]
