Answer:
$6.39
Step-by-step explanation:
Just add the cost of everything
3.18 + 1.25 + 1.96 = 6.39
y=mx+b
because the y=2x-1, so m=2
because we know (4.2), so we can bring it in to the function:
2=2x4+b
2=8+b
b=-6
So the other one is: y=2x-6
in other way it's 2x-y=6
Which means the answer is B.