The answer to this question is that the period is 6*pi/5. The period of y = sin(bx) is given by
period = 2pi/b
so with b = 3/5, that is the result.
Since you know that interior angles of one transversal add up to 180, we can subtract 72 from 180 to solve for angle DAB. 180-72=108. Our answer is angle DAB=108°
The greatest common factor for 5 and 10 is 5