David was thinking of a number. David doubles it, then adds 3 to get an answer of 81.6. What was the original number?

Add or subtract polynomial : –12qr? +13rq?

Jada has a meal in a restaurant she adds up the prices listed on the menu for everything they ordered and gets a subtotal of $42.00. after tax the total is 45.99. what percentage of the subtotal is the total?

I’m really confused and need your assist me with this question i’ve never been taught