Posted by chaya on Tuesday, April 19, 2011 at 5:09pm.
The variable d represents the cost of a customer's meal, in dollar. The following expression represents the amount paid, including tax.
d + 0.18d
F. The cost plus eighteen percent of the cost
G. the cost minus eighteen percent of the cost
H. the cost plus eight percent of the cost
J. The cost plus one hundred eighteen percent of the cost
I think the answer is F.
I really don't get this question
A merchant spend $92 to buy a calculator
then the merchant sold it with a 21% markup. Katherine used her calculator and found the amount of the markup to be $9.
Explain how you can use estimation to check the reasonableness of Katherine's
calculation
part B
Without doing calculation, tell whether or not Katherine's calculation is reasonable explain your answer
I really don't get this question can u help me

Math  Ms. Sue, Tuesday, April 19, 2011 at 5:15pm
Your first answer is right.
If you take 20% of 100, you'll get $20. It looks like Katherine's estimate is way off. 
Math  Ms. Sue, Tuesday, April 19, 2011 at 5:17pm
Another way to approach this problem is to look the relationship between 9 and 90. 9 is 10% of 90, right?

Math  chaya, Tuesday, April 19, 2011 at 5:18pm
thanks your great

Math  Ms. Sue, Tuesday, April 19, 2011 at 5:21pm
You're very welcome. :)