4z+9z 2squared + 2z + 3 combine like terms

there were 15 tiles in each box

Step-by-step explanation:

Let the number of tiles in each full box be x

Suppose, instead, that Bruce used 6 full boxes of tiles plus an additional 2 tiles. It means that he used a total of

(6x + 2) tiles

Suppose, that Felicia used 5 full boxes of tiles plus an additional 17 tiles. It means that he used a total of

(5x + 2) tiles.

If they each used the same number of tiles, it means that the total number of tiles used by Bruce = total number of tiles used by Felicia. Therefore,

6x + 2 = 5x + 17

6x - 5x = 17 - 2

x = 15