Answer
x=3
Work Step by Step
7x=21
The variable we want to solve for is x. What is being done to x?
7x
x is multiplied by 7.
To find the original value of x, we must undo what was done to x.
To undo multiplication by 7 we can divide by 7. Remember whatever you do to one side in an equation you must do to the other side to preserve the equality.
Divide both sides by 7
$\frac{7x} {7}$ = $\frac{21} {7}$
Simplify both sides by dividing numerator and denominator by 7.
$\frac{7x} {7}$ = $\frac{x} {1}$ =x, $\frac{21} {7}$ =3
So the equation simplifies to
x=3
Check your answer:
7x=21
Replace x with your solution:3
7(3)=21
Simplify
21=21
It checks so the solution (x=3) is good!
