Look at the result $\Large{K_{13} = \frac{2}{1}}$
I am explaining. Pls give me time
here in $\Large{K_{13}}$ , $\Large{\Delta{V_1} = 2}$ and $\Large{\Delta{V_3} = 1}$
In $\Large{K_{12} = \frac{1}{2}}$
Here, in $\Large{K_{12}}$ , $\Large{\Delta{V_1} = 1}$ and $\Large{\Delta{V_2} = 2}$
How the above $K_{12}$ and $K_{13}$ gave the constant $K_{23}$ in terms of object1
idk how to explain it further. But i can clearly see. what ever the ratio of $K_{12}$ and $K_{13}$. we need to make $m_1 = 1$ magnitude. Despite the fact $\Delta{V_1}$ is different in both $K_{12}$ and $K_{13}$
it automatically defined $m_1 = 1$
I think i confused you. By not explaining problem clearly.