Question

7. Christa's friend Edrei takes the bus to school. She starts at a distance of 8 miles from the school. After 10 minutes on the bus, she is 4 miles from the school. After 20 minutes, she is O miles from the school. Use the steps to find the equation that describes Edrei's distance from school as she rides the bus 1. Find the slope of the line using the points (10, 4) and (20,0). Show your work. 2. Identify the starting value, b. I 3. Write the equation that represents this situation in the form y= mx + b. Key Terms

Answer 1

from the question

Edrei takes a bus to school

and the miles he journey are

(10,4) and (20,0)

to get the slope

slope = y2 - y1 / x2 - x1

x1 = 10, y1= 4, x2= 20, and y2 = 0

slope = 0 - 4 / 20 - 10

slope = -4 / 10

slope = -2/5

The slope is -2/5

from equation of a straight line

y = mx + b

y - y1 = m(x - x1)

y1 = 4 and x1 = 10

y - 4 = -2/5(x - 10)

y -4 = -2*x/5 + 2*10/5

y - 4= -2x + 20/5

cross multiplication

5(y - 4) = -2x + 20

5y - 20 = -2x + 20

5y = -2x + 20 + 20

5y = -2x + 40

divide all through by 5

5y/5 = -2x/5 + 40/5

y = -2x/5 + 8

the equation of the situation

y = -2/5x + 8

From the equation the starting point is 8

b= 8