Solve 3x − 4 = 56

The solution of 3x − 4 = 56 is x = 20.

3x - 4 = 56\ \Rightarrow\ x = 20

Explain it step by step in chat Make a short video of it

The lines y = 3x − 4 and y = 56 meet at x = 20. 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.
$3x - 4 = 56$
2
Add 4 to both sides:
$3x - 4 + 4 = 56 + 4 \ \Rightarrow\ 3x = 60$
3
Divide both sides by 3:
$\frac{3x}{3} = \frac{60}{3} \ \Rightarrow\ x = 20$
4
Check: put x = 20 back into the equation.
$3\cdot20 - 4 = 60 - 4 = 56 \checkmark$

LaTeX source of the formulas on this page

\[ 3x - 4 = 56\ \Rightarrow\ x = 20 \]
\[ 3x - 4 = 56 \]
\[ 3x - 4 + 4 = 56 + 4 \ \Rightarrow\ 3x = 60 \]
\[ \frac{3x}{3} = \frac{60}{3} \ \Rightarrow\ x = 20 \]
\[ 3\cdot20 - 4 = 60 - 4 = 56 \checkmark \]

Trying values of x in 3x − 4 = 56

x	3x − 4	Equals 56?
18	50	no
19	53	no
20	56	yes
21	59	no
22	62	no

Questions

What is x in 3x − 4 = 56?

The solution of 3x − 4 = 56 is x = 20.

How do you solve 3x − 4 = 56?

Add 4 to both sides to get 3x = 60, then divide both sides by 3 to get x = 20.

How do I check the answer?

Replace x by 20: 3(20) − 4 = 56, which is 56.

Solve 3x − 4 = 56

How to work it out

Trying values of x in 3x − 4 = 56

Questions

Similar equations