Alvin had thrice as many marbles as John.

After Alvin gave away 380 marbles to his brother, he still had 120 marbles more than John.

(a) Find the number of marbles that Alvin has now.

(b) Find the average number of marbles Alvin and John have now.

Notes to students:
1. If the question above has parts, (e.g. (a) and (b)), given that the answer for part (a) is 10 and the answer for part (b) is 12, give your answer as:10,12

2.  Round your answer off to 2 decimal places