Solve 7x − 13 = 120

The solution of 7x − 13 = 120 is x = 19.

7x - 13 = 120\ \Rightarrow\ x = 19

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The lines y = 7x − 13 and y = 120 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.
$7x - 13 = 120$
2
Add 13 to both sides:
$7x - 13 + 13 = 120 + 13 \ \Rightarrow\ 7x = 133$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{133}{7} \ \Rightarrow\ x = 19$
4
Check: put x = 19 back into the equation.
$7\cdot19 - 13 = 133 - 13 = 120 \checkmark$

LaTeX source of the formulas on this page

\[ 7x - 13 = 120\ \Rightarrow\ x = 19 \]
\[ 7x - 13 = 120 \]
\[ 7x - 13 + 13 = 120 + 13 \ \Rightarrow\ 7x = 133 \]
\[ \frac{7x}{7} = \frac{133}{7} \ \Rightarrow\ x = 19 \]
\[ 7\cdot19 - 13 = 133 - 13 = 120 \checkmark \]

Trying values of x in 7x − 13 = 120

x	7x − 13	Equals 120?
17	106	no
18	113	no
19	120	yes
20	127	no
21	134	no

Questions

What is x in 7x − 13 = 120?

The solution of 7x − 13 = 120 is x = 19.

How do you solve 7x − 13 = 120?

Add 13 to both sides to get 7x = 133, then divide both sides by 7 to get x = 19.

How do I check the answer?

Replace x by 19: 7(19) − 13 = 120, which is 120.

Solve 7x − 13 = 120

How to work it out

Trying values of x in 7x − 13 = 120

Questions

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