Trigonometry Graphing Y=sinx etc

Y=4sin(x/6 + pi/2)-2 is the general problem but to make I need to take out the (x/6) and then the problem looks like this y=4sin1/6(x+ pi/3)-2

I dont understand how you take out the 1/6 and the pi/2 becomes pi/3 ??? Can someone explain it to me? Its just not clicking.