Solve 12x − 7 = 221

The solution of 12x − 7 = 221 is x = 19.

12x - 7 = 221\ \Rightarrow\ x = 19

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The lines y = 12x − 7 and y = 221 meet at x = 19. The solution of the equation is the x-coordinate of the point where the two sides are equal.

How to work it out

1
The goal is to get x alone. Undo the operations in the opposite order: first the subtraction, then the multiplication.
$12x - 7 = 221$
2
Add 7 to both sides:
$12x - 7 + 7 = 221 + 7 \ \Rightarrow\ 12x = 228$
3
Divide both sides by 12:
$\frac{12x}{12} = \frac{228}{12} \ \Rightarrow\ x = 19$
4
Check: put x = 19 back into the equation.
$12\cdot19 - 7 = 228 - 7 = 221 \checkmark$

LaTeX source of the formulas on this page

\[ 12x - 7 = 221\ \Rightarrow\ x = 19 \]
\[ 12x - 7 = 221 \]
\[ 12x - 7 + 7 = 221 + 7 \ \Rightarrow\ 12x = 228 \]
\[ \frac{12x}{12} = \frac{228}{12} \ \Rightarrow\ x = 19 \]
\[ 12\cdot19 - 7 = 228 - 7 = 221 \checkmark \]

Trying values of x in 12x − 7 = 221

x	12x − 7	Equals 221?
17	197	no
18	209	no
19	221	yes
20	233	no
21	245	no

Questions

What is x in 12x − 7 = 221?

The solution of 12x − 7 = 221 is x = 19.

How do you solve 12x − 7 = 221?

Add 7 to both sides to get 12x = 228, then divide both sides by 12 to get x = 19.

How do I check the answer?

Replace x by 19: 12(19) − 7 = 221, which is 221.

Solve 12x − 7 = 221

How to work it out

Trying values of x in 12x − 7 = 221

Questions

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