Solve 7x + 1 = 85

The solution of 7x + 1 = 85 is x = 12.

7x + 1 = 85\ \Rightarrow\ x = 12

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The lines y = 7x + 1 and y = 85 meet at x = 12. 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 addition, then the multiplication.
$7x + 1 = 85$
2
Subtract 1 from both sides:
$7x + 1 - 1 = 85 - 1 \ \Rightarrow\ 7x = 84$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{84}{7} \ \Rightarrow\ x = 12$
4
Check: put x = 12 back into the equation.
$7\cdot12 + 1 = 84 + 1 = 85 \checkmark$

LaTeX source of the formulas on this page

\[ 7x + 1 = 85\ \Rightarrow\ x = 12 \]
\[ 7x + 1 = 85 \]
\[ 7x + 1 - 1 = 85 - 1 \ \Rightarrow\ 7x = 84 \]
\[ \frac{7x}{7} = \frac{84}{7} \ \Rightarrow\ x = 12 \]
\[ 7\cdot12 + 1 = 84 + 1 = 85 \checkmark \]

Trying values of x in 7x + 1 = 85

x	7x + 1	Equals 85?
10	71	no
11	78	no
12	85	yes
13	92	no
14	99	no

Questions

What is x in 7x + 1 = 85?

The solution of 7x + 1 = 85 is x = 12.

How do you solve 7x + 1 = 85?

Subtract 1 from both sides to get 7x = 84, then divide both sides by 7 to get x = 12.

How do I check the answer?

Replace x by 12: 7(12) + 1 = 85, which is 85.

Solve 7x + 1 = 85

How to work it out

Trying values of x in 7x + 1 = 85

Questions

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