Help with grade 8 math? ( percent problems )?

The Percent decrease is the amount decreased by over the original amount

79.9 - 75.9 = 4.0 decrease

4 divided by 79.9 = .05006...

Percent decrease is ~0.05%

Do the same thing for the other one, I'm assuming the spaces are commas

128800 - 122000 = 6800

6800 / 128800 = .05279....

Percent decrease is ~0.052%

Basically, to understand these questions, let's first discuss percent. If you have the number 50 and you're told the number changed to 43. Well, first of all, let's clarify things. Percentage is expressing a value or number out of 100. For example, if you had a test that was worth 20 marks, and you got 15 marks, all you have do do is change that so it's out of 100. It's easy to see that by multiplying 20 by 5, we get 100. Now because we multiplied 20 by 5 to get 100, we have to multiply 15 too!

15 x 5 is 75. 15/20 is the same as 75/100, or 75%. If you had a more difficult number, such as 23 out of 77, simply divide the two numbers, 23 and 77, to get what percent of 77 23 is. Back yo your questions, if the number 79.9 changes to 75.9, we want to find how much it changed by. To do this, subtract 75.9 from 79.9 to get 4. Now, divide 4 by 79.9 to see what the percentage is.

a,79.9-75.9/79.9*100=5% the method is just to substract the decreased price from the original price/original price*100

b,128800-122000/128800*100=5.27~5.3%

Read this page (it's very short and simple, so don't worry)

I would give you the answer, but it would be much more beneficial this way.

Just read the steps on this page carefully, and follow through. It's very easy

Also at the end, they have two practice problems if you are interested.

(This focuses on increase AND decrease)

http://www.algebralab.org/Word/Word.aspx?file=Alge...