You can put this solution on YOUR website! Look at all of the possible outcomes, there are 2^4 or 16 of them and mark the ones with more than 1 B.
BBBB X
BBBG X
BBGB X
BBGG X
BGBB X
BGBG X
BGGB X
BGGG
GBBB X
GBBG X
GBGB X
GBGG
GGBB X
GGBG
GGGB
GGGG
.
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