Marisa is walking from her home to her friend Sanjay's home. When she is 12 blocks away from Sanjay's home, she looks at her watch. She looks again when she is 8 blocks away from
Sanjay's home and finds that 6 minutes have passed.

Step-by-step explanation:

A. We must consider that Marisa is walking a straight trail so that the time required to cover a distance is persistent or constant.

B. The slope of the line is: y = m x + b

Where in this problem, y is the distance, m is the slope or the time it takes for each block, x is the time, and b would be the y intercept or the initial location of Marisa.

C. The slope m can be calculated using the formula:

m = (y2 – y1) / (x2 – x1)

m = (8 – 12) / (6 – 0)

m = -0.67

The negative sign is the space between Marisa and Sanjay’s home is declining by time. It further means that there is a cut in 0.67 blocks per minute.

D. y = - 0.67 x + b

The starting point of Marisa is at 12 blocks away from Sanjay’s home, therefore let b be 12.

Finding for time when distance is y = 0:

0 = -0.67 x + 12

x = 17.9 minutes

Therefore it takes approximately 17.9 minutes to go to Sanjay’s home.