Two right angles? that's what I would think
Could it be Red Blue Blue Green Purple? Or Red Blue Green Grey Purple?
If there are 70 chairs but only 20 rows then that means he will have to set up 3.5 chairs per row, or Brook could set up 14 rows with 5 chairs in each row.
Srry if that didn't help but that's what i got from that.
Answer:
How many people are not allergic to any of the three choices? 22
How many people are allergic to all three choices? 1
How many people are allergic to both dogs and cats but not allergic to pollen? 7
How many people are allergic to cats only? 18
