Because the sofa usually sells for $800, we know that's 100% of the price.
100% = $800
Let's find 1%.
1% = $800/100
1% = $8
Next, multiply $8 by 75 to find the percent of the sofas price when it's $600.
75% = $600
We now know that $600 is 75% of the sofas original price.
100% - 75% = 25%
The percent of decrease I'm the sofas sale price is 25%.
Hope I got that right, the question was worded a little strangley so I wasn't quite sure what you were asking :)
Use the formula:

B refers to the base and H refers to the height of the triangle.
As such, multiply both the base and height of the triangle and divide the answer by 2, to find the area of the triangle.
Here is the answer from SparkNotes
http://www.sparknotes.com/math/algebra2/operationsonfunctions/section3.rhtml
Answer:
21 is 84% to 25, so there would be 25 total questions on the test
Answer:
True
Step-by-step explanation:
The sum of measures of these three angles of any triangle is invariably equal to the straight angle, also expressed as 180 °.
24+30+126=180