Solve 3x + 4 = 64
The solution of 3x + 4 = 64 is x = 20.
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.
- 2
Subtract 4 from both sides:
- 3
Divide both sides by 3:
- 4
Check: put x = 20 back into the equation.
LaTeX source of the formulas on this page
\[ 3x + 4 = 64\ \Rightarrow\ x = 20 \]
\[ 3x + 4 = 64 \]
\[ 3x + 4 - 4 = 64 - 4 \ \Rightarrow\ 3x = 60 \]
\[ \frac{3x}{3} = \frac{60}{3} \ \Rightarrow\ x = 20 \]
\[ 3\cdot20 + 4 = 60 + 4 = 64 \checkmark \]Trying values of x in 3x + 4 = 64
| x | 3x + 4 | Equals 64? |
|---|---|---|
| 18 | 58 | no |
| 19 | 61 | no |
| 20 | 64 | yes |
| 21 | 67 | no |
| 22 | 70 | no |
Questions
What is x in 3x + 4 = 64?
The solution of 3x + 4 = 64 is x = 20.
How do you solve 3x + 4 = 64?
Subtract 4 from 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 = 64, which is 64.