Answer: p = -2w + 20
Step-by-step explanation:
If the student had 20 pencils but now has 18 pencils, he uses pencils at a rate of 2 per week. So, m = -2 (negative because he is decreasing the amount of pencils). The student started with 20 pencils so b = 20
Use the y = mx + b but replace "y" with "p" and replace "x" with "w" and input the m and b as stated above:
p = -2w + 20