please help me with math!?

Question

Virgin Records stores have a new pricing policy on newly released CDs. Single CDs will sell for $11.99 and double -album CDs will sell for $18.99. The clerk rang up $66.95 before tax.

Determine what combination of CDs you purchased and calculate the total amount paid when taxes are 7.75%

please show me step by step or just the answer.

Answer 1

The 9 in the units column of both prices and the 5 in the total suggest that you bought 5 albums.

Work with 12, 19 and 67

How can you combine 12 and 19 to get 67?

4 x 12 + 1 x 19 = 67
48 + 19 = 67

so, that's it.
4 cheapys and 1 expensive.

Note the benefit of using whole numbers rather than the 99 cents stuff.

Answer 2

Do the question by trail and error.
S - single CD.
D - double CD.

No. of D + No. of S = Price.
4D + 0S = 75∙96 x
3D + 1S = 56∙97 + 11∙99 = 68∙96 x
2D + 2S = 37∙98 + 23∙98 = 61∙96 x
1D + 3S = 18∙99 + 35∙97 = 54∙96 x
1D + 4S = 18∙99 + 47∙96 = $66∙95 √

66∙95 + 7∙75% = 66∙95 + 5∙188 625
66∙95 + 7∙75% = 72∙138 625
66∙95 + 7∙75% ≈ $72∙14

Answer 3

Dear CXVZ:

When I look at the prices of the single and double album CDs, I START with the SMALLEST price or number first : $11.99. This is how I logic it out :

How many $11.99s can I get to go into the Total of $66.95? I got up to 4 of them. Because, right at that point - I could see there was room for one double album left. Bingo!

If I had been unable to fit in the one double album, I would have reversed my logic and looked at how many large CDs I could fit into the total price. Then see how many single CDs I could fit in ! So, we have to juggle these to find the answer. I ALWAYS start with the SMALLEST price or number FIRST to see how many I can fit in and what is still left over. But you can start working it out either way you like. Do you see that I could not go further than 4 single CDs and still fit in a double CD? I have to stop at 4 singles to have room for a mix of 1 double and 4 singles. You are suppose to have a mix.

Now, take the TOTAL and multiply by the percent of tax to see total tax to pay:

$66.95
X7.75
Answer is: $5.18. BUT, you will see there is another 8 behind the 18 cents - when YOU figure it. That means I should round UP to 19 cents instead of the 18 cents. So, to be real accurate - our tax total is $5.19. Remember, anytime a figure unit behind the cents is a 5 or higher - you round up to the next figure.

If you add the tax total of $5.19 to the price you will get $72.14.

$66.95
+ 5.19
Answer is: $72.14.

Love, Lana