5
1) Translating that into a mathematical expression, we can write out the following. Let's call this number by "n":
[tex]\begin{gathered} I)7n-1 \\ II)9+5n \\ 7n-1=9+5n \\ 7n-5n=9+1 \\ 2n=10 \\ \frac{2n}{2}=\frac{10}{2} \\ n=5 \end{gathered}[/tex]Just one mistake: when we refer to the same number we use the same variable.
