16. Nasser has 904 building bricks. He used 477 to build a castle. Then he used 213 more building bricks he found in a storage box. How many building bricks were not used for the castle? Show your work. Use a letter to represent the unknown.​

Answer 1

Let's represent the unknown number of building bricks that were not used for the castle with the letter "x".
We know that Nasser initially had 904 building bricks and he used 477 to build the castle.
So the number of building bricks that were not used for the castle is x = 904 - 477.
After finding 213 more building bricks, Nasser used a total of 477 + 213 = 690 building bricks.
Therefore, the number of building bricks that were not used for the castle is x = 904 - 690.
By calculating, x = 214.
So, there were 214 building bricks that were not used for the castle.