Physics sine equation?

Question

An equation for a sine wave traveling in the -x-direction can be written as:

y(x,t) = (a m)sin[( b s-1)t + (c m-1)x]

If a sine wave has an of amplitude 0.13 m, a wavelength of 0.2 m, and wave speed of 6.5 m/s; calculate the constants a, b, and c as shown in the above equation.

Answer 1

a is amplitude = 0.13 m

b is angular rate = 2pi*f, where f = wavespeed/wavelength, so b = 2pi*6.5/0.2 rad/s

cx is additional phase angle due to displacement from origin

= 2pi*number of cycles displacement = 2pi*-x/wavelength,

so c = -2pi/0.2 rad/m