Solve 7x − 14 = 77

The solution of 7x − 14 = 77 is x = 13.

7x - 14 = 77\ \Rightarrow\ x = 13

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The lines y = 7x − 14 and y = 77 meet at x = 13. 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.
$7x - 14 = 77$
2
Add 14 to both sides:
$7x - 14 + 14 = 77 + 14 \ \Rightarrow\ 7x = 91$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{91}{7} \ \Rightarrow\ x = 13$
4
Check: put x = 13 back into the equation.
$7\cdot13 - 14 = 91 - 14 = 77 \checkmark$

LaTeX source of the formulas on this page

\[ 7x - 14 = 77\ \Rightarrow\ x = 13 \]
\[ 7x - 14 = 77 \]
\[ 7x - 14 + 14 = 77 + 14 \ \Rightarrow\ 7x = 91 \]
\[ \frac{7x}{7} = \frac{91}{7} \ \Rightarrow\ x = 13 \]
\[ 7\cdot13 - 14 = 91 - 14 = 77 \checkmark \]

Trying values of x in 7x − 14 = 77

x	7x − 14	Equals 77?
11	63	no
12	70	no
13	77	yes
14	84	no
15	91	no

Questions

What is x in 7x − 14 = 77?

The solution of 7x − 14 = 77 is x = 13.

How do you solve 7x − 14 = 77?

Add 14 to both sides to get 7x = 91, then divide both sides by 7 to get x = 13.

How do I check the answer?

Replace x by 13: 7(13) − 14 = 77, which is 77.

Solve 7x − 14 = 77

How to work it out

Trying values of x in 7x − 14 = 77

Questions

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