Solve 7x − 4 = 115

The solution of 7x − 4 = 115 is x = 17.

7x - 4 = 115\ \Rightarrow\ x = 17

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The lines y = 7x − 4 and y = 115 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.
$7x - 4 = 115$
2
Add 4 to both sides:
$7x - 4 + 4 = 115 + 4 \ \Rightarrow\ 7x = 119$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{119}{7} \ \Rightarrow\ x = 17$
4
Check: put x = 17 back into the equation.
$7\cdot17 - 4 = 119 - 4 = 115 \checkmark$

LaTeX source of the formulas on this page

\[ 7x - 4 = 115\ \Rightarrow\ x = 17 \]
\[ 7x - 4 = 115 \]
\[ 7x - 4 + 4 = 115 + 4 \ \Rightarrow\ 7x = 119 \]
\[ \frac{7x}{7} = \frac{119}{7} \ \Rightarrow\ x = 17 \]
\[ 7\cdot17 - 4 = 119 - 4 = 115 \checkmark \]

Trying values of x in 7x − 4 = 115

x	7x − 4	Equals 115?
15	101	no
16	108	no
17	115	yes
18	122	no
19	129	no

Questions

What is x in 7x − 4 = 115?

The solution of 7x − 4 = 115 is x = 17.

How do you solve 7x − 4 = 115?

Add 4 to both sides to get 7x = 119, then divide both sides by 7 to get x = 17.

How do I check the answer?

Replace x by 17: 7(17) − 4 = 115, which is 115.

Solve 7x − 4 = 115

How to work it out

Trying values of x in 7x − 4 = 115

Questions

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