(1) Seven-twelfth, because there are as many sunspots in the first pile as there are Bai Zi in the second vertebra, so there are as many albinos in the first pile as in the second vertebra. (The three piles of chess pieces are all equal), so there are as many sunspots in the first pile and the second pile as in Bai Zi (albinos and sunspots are the same pile respectively), so all the sunspots add up to one and a quarter piles. Then the albino has one and three-quarters piles. Divide by three to get seven twelfth.

(2) Because the proportion of parts produced by Party A and Party B is 3:5. So their work efficiency ratio is also 3:5. That is, the working efficiency of A is three-fifths that of B. That is, it takes 20 hours for A to do it alone, so it takes 7.5 days for them to do it together. 18 times 7.5= 135 (pieces)