Answer:
$23.10
Explanation:
First, convert the 45% to a real mathematical number. For percents, this is always done by dividing the 45% by 100%, or 45% / 100% = 0.450.
Second, find out what 45% of $42 is. This is the amount of the sale discount. This is always found by mulitplying 0.450 by the item's cost $42, like this:
0.450 x $42 = $18.90.
So for this sale, you'll save $18.90 on this item.
This means, the cost of the item to you is
$42 - $18.90 = $23.10.
Hope this helps! Comment if you are still confused!