The equetion of a wave travelling on a string is
`y = 4 sin(pi)/(2)(8t-(x)/(8))`
if x and y are in centimetres, then velocity of waves is
A. 64 cm/sec in - x direction
B. 32 cm/sec in - x direction
C. 32 cm/sec in + x direction
D. 64 cm/sec in + x direction