Solve 5x − 7 = 18

The solution of 5x − 7 = 18 is x = 5.

5x - 7 = 18\ \Rightarrow\ x = 5

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The lines y = 5x − 7 and y = 18 meet at x = 5. 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.
$5x - 7 = 18$
2
Add 7 to both sides:
$5x - 7 + 7 = 18 + 7 \ \Rightarrow\ 5x = 25$
3
Divide both sides by 5:
$\frac{5x}{5} = \frac{25}{5} \ \Rightarrow\ x = 5$
4
Check: put x = 5 back into the equation.
$5\cdot5 - 7 = 25 - 7 = 18 \checkmark$

LaTeX source of the formulas on this page

\[ 5x - 7 = 18\ \Rightarrow\ x = 5 \]
\[ 5x - 7 = 18 \]
\[ 5x - 7 + 7 = 18 + 7 \ \Rightarrow\ 5x = 25 \]
\[ \frac{5x}{5} = \frac{25}{5} \ \Rightarrow\ x = 5 \]
\[ 5\cdot5 - 7 = 25 - 7 = 18 \checkmark \]

Trying values of x in 5x − 7 = 18

x	5x − 7	Equals 18?
3	8	no
4	13	no
5	18	yes
6	23	no
7	28	no

Questions

What is x in 5x − 7 = 18?

The solution of 5x − 7 = 18 is x = 5.

How do you solve 5x − 7 = 18?

Add 7 to both sides to get 5x = 25, then divide both sides by 5 to get x = 5.

How do I check the answer?

Replace x by 5: 5(5) − 7 = 18, which is 18.

Solve 5x − 7 = 18

How to work it out

Trying values of x in 5x − 7 = 18

Questions

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