Answer:
see explanation
Step-by-step explanation:
(a)
The equation of a line in slope- intercept form is
y = mx + c ( m is the slope and c the y- intercept )
Calculate m using the slope formula
m = 
with (x₁, y₁ ) = (0, 100) and (x₂, y₂ ) = (2, 200) ← 2 points on the line
m =
=
= 50
The line crosses the y- axis at (0, 100 ) ⇒ c = 100
y = 50x + 100 ← equation of line
where y is monthly savings and x the time in months
(b)
Slope is the monthly deposit , that is $50 per month
The y- intercept indicates the original amount in her account , that is $100