Solve the all parts of given question:
Question: A wave on a string is described by D(x,t)=(3.6cm)x sin[2(pi)(x/(8.4m)+t/(0.12s)+1)], where x is in m and t is in s.]
Part I: What is the wave speed?
Part II: What is the frequency?
Part III: What is the wave number?
Part IV: At t=0.42s, what is the displacement of the string at x=4.9m?
Please use as much detail as possible in answer! Thanks.