Can someone help me pleaseee

Empty box + box + empty box fill in the box is equal to 30 how

What is the factored form of the following expressions? d^2 – 13d + 36

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. when the check comes, it says they also need to pay $3.99 in sales tax. what percentage of the subtotal is the sales tax