please help. seriously helpless here!

The total quantity of chestnuts is (5/6)kg. If she roasted (3/10) of them, then that implies she
**did not** roast **(7/10)**.

If the amount **roasted** is 3/10 of 5/6 kg, that means (3/10)*(5/6) = 15/60 = 1/4 kg.

Therefore, the amount **not roasted** is (7/10)*(5/6) = 35/60 = 7/12 kg.

Note that the amount roasted + not roasted should sum to the original amount:

15/60 + 35/60 = 50/60 = 5/6 kg.