We know that
• Deon has 22 new magazines.
,• M, represents the number of magazines left.
,• R, represents the number of magazines already read.
So, if he already read 12 magazines, we define the following equation.
[tex]\begin{gathered} M+R=22 \\ M+12=22 \\ M=22-12 \\ M=10 \end{gathered}[/tex]