Solve 7x − 5 = 51

The solution of 7x − 5 = 51 is x = 8.

7x - 5 = 51\ \Rightarrow\ x = 8

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The lines y = 7x − 5 and y = 51 meet at x = 8. 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.
$7x - 5 = 51$
2
Add 5 to both sides:
$7x - 5 + 5 = 51 + 5 \ \Rightarrow\ 7x = 56$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{56}{7} \ \Rightarrow\ x = 8$
4
Check: put x = 8 back into the equation.
$7\cdot8 - 5 = 56 - 5 = 51 \checkmark$

LaTeX source of the formulas on this page

\[ 7x - 5 = 51\ \Rightarrow\ x = 8 \]
\[ 7x - 5 = 51 \]
\[ 7x - 5 + 5 = 51 + 5 \ \Rightarrow\ 7x = 56 \]
\[ \frac{7x}{7} = \frac{56}{7} \ \Rightarrow\ x = 8 \]
\[ 7\cdot8 - 5 = 56 - 5 = 51 \checkmark \]

Trying values of x in 7x − 5 = 51

x	7x − 5	Equals 51?
6	37	no
7	44	no
8	51	yes
9	58	no
10	65	no

Questions

What is x in 7x − 5 = 51?

The solution of 7x − 5 = 51 is x = 8.

How do you solve 7x − 5 = 51?

Add 5 to both sides to get 7x = 56, then divide both sides by 7 to get x = 8.

How do I check the answer?

Replace x by 8: 7(8) − 5 = 51, which is 51.

Solve 7x − 5 = 51

How to work it out

Trying values of x in 7x − 5 = 51

Questions

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