Solve 7x − 12 = 100

The solution of 7x − 12 = 100 is x = 16.

7x - 12 = 100\ \Rightarrow\ x = 16

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The lines y = 7x − 12 and y = 100 meet at x = 16. 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.
$7x - 12 = 100$
2
Add 12 to both sides:
$7x - 12 + 12 = 100 + 12 \ \Rightarrow\ 7x = 112$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{112}{7} \ \Rightarrow\ x = 16$
4
Check: put x = 16 back into the equation.
$7\cdot16 - 12 = 112 - 12 = 100 \checkmark$

LaTeX source of the formulas on this page

\[ 7x - 12 = 100\ \Rightarrow\ x = 16 \]
\[ 7x - 12 = 100 \]
\[ 7x - 12 + 12 = 100 + 12 \ \Rightarrow\ 7x = 112 \]
\[ \frac{7x}{7} = \frac{112}{7} \ \Rightarrow\ x = 16 \]
\[ 7\cdot16 - 12 = 112 - 12 = 100 \checkmark \]

Trying values of x in 7x − 12 = 100

x	7x − 12	Equals 100?
14	86	no
15	93	no
16	100	yes
17	107	no
18	114	no

Questions

What is x in 7x − 12 = 100?

The solution of 7x − 12 = 100 is x = 16.

How do you solve 7x − 12 = 100?

Add 12 to both sides to get 7x = 112, then divide both sides by 7 to get x = 16.

How do I check the answer?

Replace x by 16: 7(16) − 12 = 100, which is 100.

Solve 7x − 12 = 100

How to work it out

Trying values of x in 7x − 12 = 100

Questions

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