Question

How to tell the difference between direct proportion and inverse proportion

Answer 1

If two variables are in direct proportion, then as one increases, the other increases, and as one decreases, the other decreases. An example: If you're working, the amount of money you make (variable y) is in direct proportion to how many hours you work (variable x). The more hours you work, the more money you make, and vice versa. You can put these into the equation y = kx, where k is a constant rate at which x and y are directly proportional. 

If two variables are in inverse proportion, then as one increases, the other decreases, and vice versa. For example: if you take unpaid vacation from work, the number of days taken off (variable x) is in inverse proportion to the amount of money you make (variable y). The more vacation you take, the less money you'll make, and vice versa. You can put these into the equation y = k/x, where k is a constant rate at which x and y are inversely proportional.