Alguien me podría decir los modelos matemáticos​

Which table shows a proportional relationship between miles traveled and gas used?

Ateacher wanted to buy a chair, a bookshelf, two tables and a desk. she spent $900 for all five items and the chair and the desk combined 70% of her total. if the bookshelf cost $50, how much did each of the tables cost?

How many doughnuts are equal to 20 cookies.? 3 apples = 5 bananas6 cookies = 7 apples2 doughnuts = 1 banana