Answer:
-4x+7= -21
-4x= -21-7( this positive 7 will change to negative as we take in other side )
-4x = -28
Both the negative will be cancelled
4x = 28
x = 28/4
X = 7
therefore the X value is 7
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Answer:
An unknown variable by reversing the process used to form the original equation.
Step-by-step explanation:
The opposite process rule says to solve for - an unknown variable by reversing the process used to form the original equation.
If an equation indicates an operation such as addition, subtraction, multiplication, or division, solve for the unknown variable by using the opposite process.
For example:
Lets say we have to find 
Here 25 is subtracted from both sides of the equation to isolate x.

we get x = 10
Check this : 
Answer:
I can help you, just tell me what it is.
Step-by-step explanation:
Step 1: Tell me the problem
Step 2: Wait for a response.