The given problem says:
Six times the sum of a number and nine is 18.
So, let's set "n" as the unknown number.
Then, the sum of a number and nine is:
[tex]n+9[/tex]And six times this sum, is:
[tex]6(n+9)[/tex]The result of the sum is 18, so:
[tex]6(n+9)=18[/tex]Let's solve for n:
[tex]\begin{gathered} \text{ Divide both sides by 6:} \\ \frac{6(n+9)}{6}=\frac{18}{6} \\ \\ n+9=3 \\ \text{ Subtract 9 from both sides} \\ n+9-9=3-9 \\ n=-6 \end{gathered}[/tex]The number is -6.
