Solve the all parts of following question:
Question: A wave on a string is described by D(x,t)=(3.8cm)×sin[2?(x/(3.6m)+t/(0.24s)+1)], where x is in m and t is in s.
Part A: What is the wave speed?
Part B: What is the frequency?
Part C: What is the wave number?
Part D: At t=0.84s, what is the displacement of the string at x=3.9m?
Please show all intermediate steps and formulas for above question.