Question

8th grade math

Write an equation that models each situation in slope-intercept form by finding the slope and y-intercept

Steven had some money left over from his birthday. He didn't add any money to his savings but instead spent the same amount every week. After 3 weeks he $45 left. After 5 weeks he had $35 left.

Answer 1

y = -5x + 60

Explanation:

You have two ordered pairs (3, 45) and (5,35)

y = mx + b

We need to find the slope and the y-intercept

Slope:

change in y over the change in x

(3,45) (5, 35)

The y's are 35 and 45. You find the change by subtracting.

35 - 45 = -10

The x's are 5 and 3. You find the change by subtracting,

5-3 = 2

`(-10)/(2)` = -5

The slope (m) is -5

y-intercept:

Use of the on the points. I will use (3, 45)

x = 3

y = 45

slope = -5

y = mx + b Substitute in what you know and solve for b

45 = -5(3) + b

45 = -15 +b Add 15 to both sides

60 = b

The y-intercept (b) is 60.

y = -5x + 60