To solve this problem we can express one equation for each condition so the first ones is:
There are 178 more runners than bikers so:
[tex]R=B+178[/tex]whre R are the runners and B are the bikers
and the second one is:
in total there are 676 people this means that:
[tex]R+B=676[/tex]now we can replace the first equation into the second one so we have:
[tex]\begin{gathered} B+178+B=676 \\ 2B=676-178 \\ B=\frac{498}{2} \\ B=249 \end{gathered}[/tex]now we can replace B in the first equation so:
[tex]\begin{gathered} R=249+178 \\ R=427 \end{gathered}[/tex]So in total the there are 427 runners and 249 bikers