Draw a diagram to get a good grasp of the angles.
The conversion angle is 1/2 convergency.
Conv= 10 x sin 55 = 8 degrees
Conv Angle = 1/2 x 8 = 4 degrees
Convergency is the amount by which the Heading will change if you follow the GC track. So at 20W TRK 274 , at 25W TRK 270 and at 30W TRK266
It’s the conversion angle that’s applied to the Rhumb line track not convergency.