Hi there!
Here are all the steps into multiplying these 2 parentheses :
(9x + 2y) × (9x - 2y)
9x × 9x = <u>81x²</u>
9x × -2y = <u>-18xy</u>
2y × 9x = <u>18xy</u>
2y × -2y = <u>-4y²</u>
81x² - 18xy + 18xy - 4y²
-18xy + 18xy = 0
Your answer is: 81x² - 4y²
There you go! I really hope this helped, if there's anything just let me know! :)
63 can be written as 60+3