Hi there!
We can find an equation that models Amanda's savings using the equation:
y = km, where:
k = rise / run (Amount/months)
Plug in a set of values from the table:
k = 100/2 = 50
y = 50m
We know that Mary saves y = 60m dollars a month, so we can determine the correct comparison by plugging in a value of 1 month into both equations:
Amanda:
y = 50(1) = $50
Mary:
y = 60(1) = $60
The difference between Mary's and Amanda's savings is $60 - $50 = $10, so each month, Mary saves $10 more than Amanda.
The correct answer is D.