Well - I mean. If every lunch costs $4 that means that the relationship should be linear.
You used to be able to draw graphs. But plot it out.
The relationship will be a solid line.
The relationship between the number of $4 lunches you buy with a $100 school lunch card and the money remaining on the card.
The relationship will be a solid line as it is a linear and common slope. Each time you buy lunch, the amount in the card will decrease by $4.
Let the number of lunches you buy be = x
Let the amount remaining in the card be = y
So, equation forms:
When you buy 1 lunch, or x = 1
When x = 2
When x = 3
We can see that the decrease is gradual and same.
You can also see the graph attached that a straight line is formed.