Answer:
[tex]y=4\cdot{x}+20[/tex]
Step-by-step explanation:
Let the regresssion line be linear because of a constant amount of money coming in. Let y be the total amount of money in the box and x the weeks of adding to the box:
[tex]y=m\cdot{x}+c[/tex]
We know that he puts $20 in the box from his birthday and $4 every week for x weeks. Therefore the total amount of money will be:
[tex]y=4\cdot{x}+20[/tex]