SOLUTION: I need some help with deciding if the given number is a solution to the given equation and I am not sure how to know. 3x +7 = 21; 4 Thanks :O)

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Question 417575: I need some help with deciding if the given number is a solution to the given equation and I am not sure how to know.
3x +7 = 21; 4



Thanks :O)
Answer by marcovan(4) About Me  (Show Source):
You can put this solution on YOUR website!
3x+7=21
Isolate variable by subtracting 7 from both sides
3x+7=21
-7=-7
3x=14
divide both sides by 3
3x/3=14/3
x=14/3 therefore 4 is not a solution
check:
3(4)+7=21
12+7=21
19 does not equal 21 so therefore 4 is not a solution