The expansion of a perfect square is

In words, the square of a sum of two terms is the sum of the squares of the two terms (
and
), plus twice the product of the two terms (
)
So, when determining if you have a perfect square trinomial, you should have two perfect squares. Note that they don't have to be the first and third term, since you can rearrange terms as you prefer.
Answer:
12 purple rocks
24 blue rocks
Step-by-step explanation:
<u>2/3 blue</u>
<u>1/3 purple</u>
36/3 = 12