When given a problem in a real-world situation, how can you identify the slope and y-intercept?

The slope is how much something increases or decreases by at a constant rate, for example if johnny buys 3 oranges every time he goes to the store the slope would be 3. the y-intercept is how many things you start with so if johnny already had 5 oranges before he went to the store the y-intercept would be 5. the equation for that situation would by y=3x+5 ... 3x is the 3 oranges johnny buys each time he goes to the store (the slope) and 5 is how many oranges he started with before going to the store at all (y-intercept)