Answer:
y=2x-1
Step-by-step explanation:
y=mx+b
insert Point (0,-1)
-1 = m * 0 + b
-1 = b
slope:
m = delta y / delta x
m = 2 / 1
m = 2
-9-(12-3x)=-9-1*(12)-1*(-3)=-9-12+3x=-21+3x=3(x-7)
Their error is that they divided 12 by 30, instead of 30 by 12 in order to get the price per pair
the correct unit price is $2.50 per pair
2.5 * 12 = 30
Up two over one so the slope is 2