I am having difficulty with this function:

y = -2sin (2 ((t+1)/3)

I know to find the period I need to divide 360 degrees by the absolute value of b, but I can't figure out how to factor the equation properly to find the correct value of b.

I thought I could multiply both the 2, and the (t+1)/3 by 3 to eliminate the fraction, but that doesn't seem to be right.

I think I'm probably missing something fairly obvious... the other questions have been so easy!