Let x is a shortest side then other side is:
x+300 and x+400.
Perimeter = 1900
Perimeter of triangle is:
[tex]\begin{gathered} x+(x+300)+(x+400)=1900 \\ x+x+300+x+400=1900 \\ 3x+700=1900 \\ 3x=1900-700 \\ 3x=1200 \\ x=\frac{1200}{3} \\ x=400 \end{gathered}[/tex]So the sides of triangle is
[tex]\begin{gathered} 1)\rightarrow_{}x=400 \\ 2)\rightarrow x+300=400+300 \\ =700 \\ 3)\rightarrow x+400=400+400 \\ =800 \\ \end{gathered}[/tex]