Final answer:
Carson used 2x bricks for the Sydney Opera House and x bricks for the White House.
Step-by-step explanation:
Let's assume Carson used x bricks for the White House.
Since he used twice as many bricks for the Sydney Opera House, he used 2x bricks for it.
Then, the total number of bricks used is x + 2x = 3x.
Since the total number of bricks used is all the bricks available, we can set up an equation: 3x = total number of bricks.
Therefore, the answer is: Sydney Opera House - 2x bricks and White House - x bricks.