Slope-intercept form: y = mx + b [m is the slope, b is the y-intercept or the y value when x = 0 ---> (0, y) or the point where the line crosses through the y-axis]
y = 25x + 125
"y" would represent the total amount of $ she has saved.
The y-intercept would be 125 or (0, 125), this means that she already/initially had $125 in her savings account, before she started depositing $25 per week