Answer: 3x+35
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Step-by-step explanation:
1 CD costs x dollars
3 of them cost 3x dollars, where 3x means "3 times x".
For instance, if x = 14, then 3x = 3*14 = 42
Unfortunately, we don't know what x is, so we leave it as 3x.
We do know that Kyung bought 2 DVDs costing $10 each. So that's another 2*10 = 20 dollars added onto the 3x so far.
So far the total bill is 3x+20 dollars
Then we add on the $15 to represent the book purchase.
3x+20+15 = 3x+35
The expression 3x+35 represents how much money was spent total.
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Put another way:
3x = cost of the 3 CDs at x dollars each
2*10 = 20 = cost of the 2 DVDs at $10 each
15 = cost of the 1 book
total cost = CDs+DVDs+book = 3x+20+15 = 3x+35