The point-slope equation formula is [tex](y - y_1) = m(x - x_1)[/tex], where [tex]m[/tex] is the slope of the line and [tex](x_1, y_1)[/tex] is a point on the line.
In our problem, we are adding $200 for each week [tex]x[/tex], or we are changing each week by +200. This means that our slope [tex]m[/tex], which is essentially the change of the line, is 200. The problem also gave us a coordinate point on the line, which was that at week 4, or when [tex]x = 4[/tex], we have $1700 in the account, or [tex]y = 1700[/tex]. Thus, the coordinate point is [tex](4, 1700)[/tex].
Using this information, we can find the equation of the line:
[tex](y - 1700) = 200(x - 4)[/tex]
The answer is (y - 1700) = 200(x - 4).
