Express the given digits as a prime factorization.
[tex]36=2\times2\times3\times3[/tex]It can be observed that the factor of 36 does not have a factor of 7.
Similarly,
[tex]\begin{gathered} 42=2\times3\times7 \\ 54=2\times3\times3\times3 \\ 28=2\times2\times7 \\ 84=2\times2\times3\times7 \\ 77=7\times11 \end{gathered}[/tex]Observe that 42, 28, 84, and 77 have a factor of 7.
