sin 5x = 1/2
Note that the "5" "horizontally compresses" the normal sine curve by a factor of 5
So......for sin (x), there will 2 solutions on (0, 2pi) where sin x = 1/2
So....2 values in one normal period
But....we have 5 periods on (0, 2pi) for sin (5x)
So.....there will be 5(2) = 10 solutions for sin (5x) = 1/2