Given that he has saved the same amount each week, then the expression has the form of a line
The slope-intercept form of a line is:
y = mx + b
where m is the slope and b is the y-intercept.
In the context of this problem, the y-intercept is the initial amount of money, that is, b = 20
The slope of the line that passes through the points (x1, y1) and (x2, y2) is computed as follows:
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]The line passes through the points (1, 25) and (2, 30), then its slope is:
[tex]m=\frac{30-25}{2-1}=5[/tex]Therefore, the equation is:
y = 5w + 20
