24 + 36
[tex]\begin{gathered} \text{factors of 24 = }\mleft\lbrace1,2,3,4,6,8,12,24\mright\rbrace \\ \text{factors of 36 = }\mleft\lbrace1,2,3,4,6,9,12,18,36\mright\rbrace \\ \text{GCF}=12 \\ 24=12\times2 \\ 36=12\times3 \\ (12\times2)+(12\times3) \\ 24+36=12(2+3) \end{gathered}[/tex]