What is the rate of change in this equation? -12x-6y=18

Name the most appropriate metric unit for each measurement like a length of an carrot

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

Abcd is a square. what is the measure of angle bac