Since we have two bags with weight w and one backpack with 4 kg, and the total is 35 kg, we can write the equation:
[tex]2w+4=35[/tex]Solving this equation for w, we have:
[tex]\begin{gathered} 2w=35-4 \\ 2w=31 \\ w=\frac{31}{2} \\ w=15.5 \end{gathered}[/tex]So each checked bag has 15.5 kg.