x+30%x=-1,31
<=> x(0.3+1)=-1,31
<=> X=\(\frac{-1,31}{1,3}\)
<=>x.(1+30%)=-1,31
<=>x.1,31=-1,31
<=>x=-1
\(x+30\%x=-1,31\)
\(\Leftrightarrow x+\dfrac{30}{100}x=-1,31\)
\(\Leftrightarrow\dfrac{13}{10}x=-1,31\)
\(\Leftrightarrow x=-\dfrac{131}{130}\)