Question 1010497
Call hikers and bikers, h and b.  Then we have
h + b = 676  and
h = b + 178
Plugging this into the first equation gives us
b + 178 + b = 676
2b + 178 = 676
2b = 498
b = 249 bikers
h = 249 + 178 = 427 hikers