This is Evan. 
He is having a teaparty. He invited ducks , dragons , bats , and Anna 
.
The ducks each brought flowers. So there were flowers to decorate the table.
x =
The dragons each brought hot dogs. So there were hot dogs for everyone to share.
x =
Anna baked 100 cookies. The bats were snacking while setting up. They ate cookies, leaving cookies for the party.
100 - =
Let's party!