Question

You are putting away money to spend at the school carnival. On day 6, you had $5. You were able to save

$14 by day 11.
Write an equation to model your savings.
For the slope and y-intercept, it will need TWO NUMBERS after the decimal point.

Answer 1

We have the equation of the line as;

y = 1.80x - 5.80

Explanation:

Let us have a plot of the amount saved in dollars to the day number

So we have the amount as y axis values and the day as x axis values

from the question, we can identify the points as;

(6,5) and (11,14)

Mathematically the equation of a straight line can be represented by the equation;

y = mx + b

where m is the slope and b is the y intercept

So, we calculate the slope using the two points above

We have the formula as;

m = (y2-y1)/(x2-x1)

(x1,y1) = (6,5)

(x2,y2) = (11,14)

m = (14-5)/(11-6) = 9/5 = 1.8

So we have the equation as;

y = 1.80x + c

To get the value of c, we use any of the two points

Let us use the point (6,5)

we substitute 6 for x and 5 for y

So, we have ;

5 = 1.8(6) + c

c = 5-1.8(6)

c = -5.8

So we have the equation as;

y = 1.80x - 5.80