Answer
$A\cup (B\cup C)$={June,Jill,Jeffrey,Janet,Jello,Justin,Sally,Solly,Molly,Jolly}
Work Step by Step
$A \cup B$ is the set of all things that are members of either A or B
$B\cup C$={Janet,Jello,Justin,Sally,Solly,Molly,Jolly}
$A\cup (B\cup C)$={June,Jill,Jeffrey,Janet,Jello,Justin,Sally,Solly,Molly,Jolly}