Tray P has 3 rows of 5 cookies. Tray Q is the same tray turned sideways, so it has 5 rows of 3. Which statement is true?

Both trays hold the same cookies: $3\times 5=15$ and $5\times 3=15$. Changing the order of the two numbers being multiplied does not change the product — the commutative property of multiplication. (8 comes from adding $5+3.$)