The blue and brown cables each wraps 1 rev. round the orange pulley of two radii (R and r, R is larger than r).
The pulley has a revolution joint with the blue slider.
Two ends of the blue cable are fixed to the yellow slider.
Two ends of the brown cable are fixed to the immobile base.
Velocity ratio between the yellow slider (Vy) and the blue one (Vb):
Vy/Vb = (R + r)/r
For this case R = 2r so Vy = 3Vb
If R = r then Vy = 2Vb