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Solve 3x + 15 = 39

The solution of 3x + 15 = 39 is x = 8.

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The lines y = 3x + 15 and y = 39 meet at x = 82468101214202530354045505560x = 8y = 3x + 15y = 39
The lines y = 3x + 15 and y = 39 meet at x = 8. The solution of the equation is the x-coordinate of the point where the two sides are equal.

How to work it out

  1. 1

    The goal is to get x alone. Undo the operations in the opposite order: first the addition, then the multiplication.

    3x+15=393x + 15 = 39
  2. 2

    Subtract 15 from both sides:

    3x+15−15=39−15 ⇒ 3x=243x + 15 - 15 = 39 - 15 \ \Rightarrow\ 3x = 24
  3. 3

    Divide both sides by 3:

    3x3=243 ⇒ x=8\frac{3x}{3} = \frac{24}{3} \ \Rightarrow\ x = 8
  4. 4

    Check: put x = 8 back into the equation.

    3⋅8+15=24+15=39✓3\cdot8 + 15 = 24 + 15 = 39 \checkmark
LaTeX source of the formulas on this page
\[ 3x + 15 = 39\ \Rightarrow\ x = 8 \]
\[ 3x + 15 = 39 \]
\[ 3x + 15 - 15 = 39 - 15 \ \Rightarrow\ 3x = 24 \]
\[ \frac{3x}{3} = \frac{24}{3} \ \Rightarrow\ x = 8 \]
\[ 3\cdot8 + 15 = 24 + 15 = 39 \checkmark \]

Trying values of x in 3x + 15 = 39

x3x + 15Equals 39?
633no
736no
839yes
942no
1045no

Questions

What is x in 3x + 15 = 39?

The solution of 3x + 15 = 39 is x = 8.

How do you solve 3x + 15 = 39?

Subtract 15 from both sides to get 3x = 24, then divide both sides by 3 to get x = 8.

How do I check the answer?

Replace x by 8: 3(8) + 15 = 39, which is 39.

Similar equations

    Solve 3x + 15 = 39: x = 8 (steps and check) | WordGPT