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Answer variants:
\(ryyy\)
\(yyry\)
\(yrry\)
\(ryry\)
\(ryyr\)
\(yryr\)
\(yyrr\)
\(yryy\)
\(rryy\)
You have two red and two yellow blocks. How many different towers can you build that are four blocks high using these blocks? List all the possibilities.
 
[Note: Represent red colour block as '\(r\)' and yellow colour block as '\(y\)']
 
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