Answer:
4y
Step-by-step explanation;
since they have something in common which is y,it is possible to subtract.we would be focusing more on the numbers than letters.The like term which is y just paves a way for these numbers to be subtracted.Hence, 6y -2y= 4y
or you can do it this way also
they have something in common which is y,so we factorise
y(6-2)
y(4)
hence y(4) also means 4 x y= 4y