Before Chaya joined her, Garima managed to peel 12 potatoes out of the 44.

Therefore we can state that as Chaya joined, there were only 32 potatoes to peel, as 44 - (3*4) = 32

Per minute, both C and G peel a combined total of 8 potatoes, thus in 4 minutes after C joined in, all of the potatoes would have been peeled.

so for G: (3*4) + 12 = 24

and C: (5*4) = 20

20+24 = 44, the total sum of potatoes we start with.

Therefore, Garima managed to peel 24 potatoes, and Chaya managed to peel 20.