Solve 6x − 15 = 87

The solution of 6x − 15 = 87 is x = 17.

6x - 15 = 87\ \Rightarrow\ x = 17

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The lines y = 6x − 15 and y = 87 meet at x = 17. 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.
$6x - 15 = 87$
2
Add 15 to both sides:
$6x - 15 + 15 = 87 + 15 \ \Rightarrow\ 6x = 102$
3
Divide both sides by 6:
$\frac{6x}{6} = \frac{102}{6} \ \Rightarrow\ x = 17$
4
Check: put x = 17 back into the equation.
$6\cdot17 - 15 = 102 - 15 = 87 \checkmark$

LaTeX source of the formulas on this page

\[ 6x - 15 = 87\ \Rightarrow\ x = 17 \]
\[ 6x - 15 = 87 \]
\[ 6x - 15 + 15 = 87 + 15 \ \Rightarrow\ 6x = 102 \]
\[ \frac{6x}{6} = \frac{102}{6} \ \Rightarrow\ x = 17 \]
\[ 6\cdot17 - 15 = 102 - 15 = 87 \checkmark \]

Trying values of x in 6x − 15 = 87

x	6x − 15	Equals 87?
15	75	no
16	81	no
17	87	yes
18	93	no
19	99	no

Questions

What is x in 6x − 15 = 87?

The solution of 6x − 15 = 87 is x = 17.

How do you solve 6x − 15 = 87?

Add 15 to both sides to get 6x = 102, then divide both sides by 6 to get x = 17.

How do I check the answer?

Replace x by 17: 6(17) − 15 = 87, which is 87.

Solve 6x − 15 = 87

How to work it out

Trying values of x in 6x − 15 = 87

Questions

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