The sum of n terms is given from the first term and the common ratio by

For your given values of a1=-11, r=-4, n=8, the sum of 8 terms is

7 is 1/4 of 28, so 7 is 25% of 28.
The drop from 28 to 7 is a drop of 21.
21 is 3 times 7, so 21 is 3 times 25%.
Answer: It is a 75% decrease.
Use substitution.
2p + 3(2p) = 680
2p + 6p = 680
8p = 680
p = 85
Plug in.
x = 2p
x = 2(85)
x = 170
p = 85
<u>Answer:</u>
$14
<u>Step-by-step explanation:</u>
Assuming the cost of folder to be
, then the cost of notebook will be
and the cost of set of pencils will be
.
Cost of the folder = $2
Cost of notebook = 4 × 2 = $8
Cost of pencil = 2 × 2 = $4
Total cost of 1 folder, 1 notebook and 1 set of pencils = $2 + $8 + $4 = $14