Answer :
Let x be the total amount they spent.
Including Samuel, and 4 of his friends, there are five of them. This can be written in the expression.
[tex]x=5\cdot15[/tex]Divide both sides by 5, and we get
[tex]\begin{gathered} x=5\cdot15 \\ \frac{x}{5}=\frac{5\cdot15}{5} \\ \frac{x}{5}=15\text{ \lparen final answer\rparen} \end{gathered}[/tex]