Increasing and decreasing quantity by percentages

 In this lesson we're going to learn increasing and decreasing quantities in percentage.
The way we're doing it is we add the amount for example 13%, and we add to 100%.
Way of decreasing the quantity is we subtract the amount we want for example 13%, from 100%.

1. Our first example is "Increase $560 by 13%.
                                                                               [100% + 13% = 113%]
113% x $560
= 113/100 x 560
= 63280/100
= $632.80

  Therefore the answer is $632.80.

2. Second example is "Decrease $78 by 14%.
                                                                             [100% - 14% = 86%]
$78 x 86%
= 86/100 x $78
= 6708/100
= $67.08

3. Third example is "$900 is to be increased by 15% each month for the next 6 months. What will be the final amount?"

  Firstly we add 12% to 100%. We just don't do it once in this question it says for 6 months so we add 12% to 100% 6 times.

Secondly we multiply 112% to $900.

(100 + 12) x 6

= 112%  112% x 112% x 112% x 112% x 112% x $900
= $1776.440417
= $1176

4. Forth and last example is "Decrease $300 by 12%, then increase the amount by 24%.
                                                                                (100% - 12% = 88%)
                                                                                (100% + 24% = 124%)
1)  88% x $300
= 88/100 x 300
= 26400/100
= $264

2) 124% x $264
= 124/100 x 264
= 32736/100
= $327.36

Therefore the answer is $327.36