10% of $400 is:
$400* (10/100)= $40
$400- $40= $360.
The reduced price of the keyboard is $360~
Just need some points here
The total cost of 1000 CDs is: 6.45*1000=6450.
The revenue is the product of the number of CDs sold, n, and the selling price of each is 12.95.
P=12.95n-6450
I can’t see A-c can u take another picture
For rounding to the nearest 10, you look at the 1's place and determine if its over 5 or under 5. If it is under 5 you round down to the nearest ten, and if its over you go to the nearest ten. For 407, 7 is over 5, so it is 410.