Solve 3x + 9 = 60

The solution of 3x + 9 = 60 is x = 17.

3x + 9 = 60\ \Rightarrow\ x = 17

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The lines y = 3x + 9 and y = 60 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 addition, then the multiplication.
$3x + 9 = 60$
2
Subtract 9 from both sides:
$3x + 9 - 9 = 60 - 9 \ \Rightarrow\ 3x = 51$
3
Divide both sides by 3:
$\frac{3x}{3} = \frac{51}{3} \ \Rightarrow\ x = 17$
4
Check: put x = 17 back into the equation.
$3\cdot17 + 9 = 51 + 9 = 60 \checkmark$

LaTeX source of the formulas on this page

\[ 3x + 9 = 60\ \Rightarrow\ x = 17 \]
\[ 3x + 9 = 60 \]
\[ 3x + 9 - 9 = 60 - 9 \ \Rightarrow\ 3x = 51 \]
\[ \frac{3x}{3} = \frac{51}{3} \ \Rightarrow\ x = 17 \]
\[ 3\cdot17 + 9 = 51 + 9 = 60 \checkmark \]

Trying values of x in 3x + 9 = 60

x	3x + 9	Equals 60?
15	54	no
16	57	no
17	60	yes
18	63	no
19	66	no

Questions

What is x in 3x + 9 = 60?

The solution of 3x + 9 = 60 is x = 17.

How do you solve 3x + 9 = 60?

Subtract 9 from both sides to get 3x = 51, then divide both sides by 3 to get x = 17.

How do I check the answer?

Replace x by 17: 3(17) + 9 = 60, which is 60.

Solve 3x + 9 = 60

How to work it out

Trying values of x in 3x + 9 = 60

Questions

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