S = 3
Because angle B = Y as stated at the top we can assume triangle 2 is a smaller version of triangle 1.
Because the length of the same side on triangle 2 = 2 and on triangle 1 it = 4 we can assume triangle 2 is half the size of the first triangle.
So to find the length of s we divide 6 by 2 because triangle 2 is half the size of triangle 1.
This gives us 3 meaning s = 3
