This is my interpretation of the questions answer. If you are thinking of a design ten just make a snake one. Its simple but not hard.
It's the bottom one. 20 dollars has to be less than or equal to the amount. you cannot spend more than $20
You can use the slope formula or just calculate

So for the first problem you run 3 units right and rise 5 units so

2. Notice the y axis goes by 2 units.

3.

4.

Please let me know if you have questions
Answer:
keep doubling the answer by 6