We can make a system of equations with the information given:
Let x be the weight of each large box
Let y be the weight of each small box
Then,
(1) 6x+5y=115
(2) 2x+3y=47
Now, we are going to isolate one variable on one of the equations, and then substite on the other:
(2) 2x=47-3y
x=47/2-3/2y
Now, we are going to substitute (2) in (1)
[tex]\begin{gathered} 6(\frac{47}{2}-\frac{3}{2}y)+5y=115 \\ 141-9y+5y=115 \\ 141-4y=115 \\ 141-115=4y \\ \frac{26}{4}=y \\ y=6.5 \end{gathered}[/tex]
Then, having the weight of each small box, we are going to substitute y=6.5 in (2)
[tex]\begin{gathered} 2x+3(6.5)=47 \\ 2x+19.5=47 \\ 2x=47-19.5 \\ x=\frac{27.5}{2} \\ x=13.75 \end{gathered}[/tex]
Each large box weighs 13.75 kg and each small box weighs 6.5 kg.