The given expression is,
[tex]40x+24y-56[/tex]The factors of 40, 24 and 56 are,
[tex]\begin{gathered} 40\colon2,4,5,8,10 \\ 24\colon2,4,3,8 \\ 56\colon2,4,7,8 \end{gathered}[/tex]The greatest common factor is therefore, 8.
Therefore, the given expression can be written as,
[tex](8\times5)x+(8\times3)y-(8\times7)[/tex]Taking 8 as common, we have,
[tex]8(5x+3y-7)[/tex]