Question about phase constant

we have the wave equation as follows with non zero phase constant:


y(x,t) = ym * sin(k( x - PHI/k) - wt)
or

y(x,t) = ym * sin(kx - w(t + PHI / w))

I don't understand where did the PHI /k or PHI / w came from ??

I understand how did we derive the wave equation but I don't understand this part.