4) Alice and Bob have 300 coins in total in their collections. Alice gave Bob 30 coins, and Bob gave Alice 20 coins. Now Bob has twice as many coins as Alice. How many coins did hey initially have in their collections? a) 200 in Alice's collection, 100 in Bob's collection. b) 110 in Alice's collection, 190 in Bob's collection. c) 150 in Alice's collection, 150 in Bob's collection. d) 120 in Alice's collection, 180 in Bob's collection