Just multiply the cost by the tax rate (use the decimal fraction 0.0625 for this):
0.0625($498) = answer
Since
is a group,
•
has an identity element
such that
for all 
• there is an inverse
for every
such that 
• for any
, we have the associative property 
a) Given that
, we have

Since
, which means
, we get that

Then

as required.
b) What do you mean by "rank of an element in a group"? That doesn't sound like a standard concept as far as I know.
Answer:
y= -3x + 14
Step-by-step explanation:
m=-3
x=4
Y=2
Y=mx+b
2=-3(4)+b
2=-12+b
You add +12 in both side and you get
14=b