Roger wants to have 400 copies of his resume printed. his local print shop charges $21.50 for the first 200 copies and $10 for every 100 additional copies. how much will the 400 copies cost, including a sales tax of 6%

Step-by-step explanation:

We'll d the sales tax last.

So, assumedly 1-200 will cost that base 21.50 regardless, so if we say the first 200 is 21.50 that means the remaining 200 will get the other price.  The other price is 10 dollars per 100.  So 200 is 100 twice, so that's 10 dollars twice, which is 20.

This leaves 41.50 as the base price.  Now to find the sales tax you multiply the base price by the tax percentage in decimal form.  6% is .06 in decimal form.  So you do 41.50*.06 = 2.49.  That is how much is being added.  so now the full price is 41.50+2.49 = 43.99.

Anther way to find sales tax is this formula b(1+t) where b is the base price and t is the tax in decimal form.  So for this you could have done 41.50(1+.06).

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