Tìm x: x + 30% = -1,3

x + 30% =-1,3

x + $\frac{30}{100}$ =$\frac{-13}{10}$ 

x + $\frac{3}{10}$ =$\frac{-13}{10}$ 

x = $\frac{-13}{10}$ - $\frac{3}{10}$

x = $\frac{-16}{10}$ 

x = $\frac{-8}{5}$ 

Vậy : x = $\frac{-8}{5}$