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
P² - 12 p - 13 = 0
Δ = ( -12)² - 4 ( 1 * - 13)
Δ = 144 + 52
Δ = 196 = 14²
x₁ = (- ( -12) + 14 ) / 2 = 26/2 = 13
x₂ = ( - ( -12) - 14) /2 = - 2 /2 = - 1
S = 13