With an equation you must isolate x or whatever the variable is. Operations are the things used to make the difference like +,-,x,/.
A great example of this is the following
4x-12=0
First add 12 to both sides making the equation go to
4x=12
now divide 4 from both sides making
x=3
It increased a total of 4 inches.
Answer:
The answer to your question is
a) Poster width = 3 in
lenght = 9 in
b) banner
width = 2 in
lenght = 10 in
Step-by-step explanation:
a) For the poster
width = x
lenght = 3x
Perimeter of a rectangle = 2base + 2 height
= 2(x) + 2(3x) = 24
2x + 6x = 24
8x = 24
x = 24/8
x = 3
width = 3 in
lenght = 3(3) = 9 in
b) For the banner
width = y
lenght = 5y
Perimeter of a banner = 2 base + 2 height
2 (y) + 2(5y) = 24
2y + 10y = 24
12y = 24
y = 24/12
y = 2
width = 2 in
lenght = 5(2) = 10 in
The scenario will will be represented by: 
The number will be -13
Step-by-step explanation:
We have to convert the given situation into the mathematical form
Let x be the number
Then
"a number plus itself"
x+x
"plus twice itself"
x+x+2x
"plus 4 times itself"
x+x+2x+4x
"is equal to -104"

This can also be written as:

Keywords: Linear Equation
Learn more about linear equation at:
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The number 5 is 90 degrees, acute