How do you know when to multiply and when to divide to convert units of measurement

Atriangle with all sides of equal length is a/an triangle. a. right b. scalene c. equilateral d. isosceles

Twenty points. suppose that one doll house uses the 1 inch scale, meaning that 1 inch on the doll house corresponds to 1/2 foot for life-sized objects. if the doll house is 108 inches wide, what is the width of the full-sized house that it's modeled after? in inches and feet

You are at a restaurant and owe $56.20 for your meal. you want to leave an 18% tip. approximately how much is your tip?