Question

David and Amanda are trying to figure out how long they can live off their $12,350 savings if they spend $240 each month. They have each created an equation.
David’s Equation Amanda’s Equation
y = 12,350 – (240x) y = 12,350 + (240x)

Which person has the correct equation to model this linear relationship?
Amanda’s equation is correct, because their spending will be multiplied by the number of months and then added to their savings.
Amanda’s equation is incorrect, because their spending will increase the amount of their savings.
David’s equation is correct, because their spending will be multiplied by the number of months and then subtracted from their savings.
David’s equation is incorrect, because their spending should be a fixed amount and should not be multiplied.

Answer 1

Well, the question wants to know how long they can live of $12 350 if they SPEND $240 each month.

So, we say let x = month.
If we want to know how long they can live off $12 350, we'd have to subtract 240x .

Answer 2

Soooo immediately you should know that Amanda's equation is wrong because we have to subtract 240 per month rather than ADD that to the original amount of savings.
What do you think the answer will be ?