Question

Ethan has some money in his savings account when he starts his new job as a Jimmy John's delivery guy. After starting, he decides to save the same amount from his paycheck each month. After 3 months, Ethan has 560 dollars in his savings, and after 6 months, he has 920 dollars. Find an equation that gives the amount saved ("y") after "x" months.

Answer 1

y = 360x+200

Explanation:

We will use the concept of finding the equation of a line using two coordinates (x1,y1) and (x2,y2)

If after 3 months, ethan has 560 dollars in his savings, and after 6 months, he has 920 dollars, this can be represented as coordinate points (3,560) and (6,920)

The equation of a line in point slope form is expressed as;

y = mx+c

m is the slope = ∆y/∆x = 920-560/6-3

m = 360/3

m = 120

Get the intercept;

Substitute m = 120 and any of the points to get c, using the point (3,560)

x = 3, y = 560

560 = 120(3)+c

560 = 360+c

c = 560-360

c = 200

Get the required equation by substituting m and c into y = MX+c

y = 360x+200