Solve 3x − 5 = 40

The solution of 3x − 5 = 40 is x = 15.

3x - 5 = 40\ \Rightarrow\ x = 15

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

The lines y = 3x − 5 and y = 40 meet at x = 15. 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.
$3x - 5 = 40$
2
Add 5 to both sides:
$3x - 5 + 5 = 40 + 5 \ \Rightarrow\ 3x = 45$
3
Divide both sides by 3:
$\frac{3x}{3} = \frac{45}{3} \ \Rightarrow\ x = 15$
4
Check: put x = 15 back into the equation.
$3\cdot15 - 5 = 45 - 5 = 40 \checkmark$

LaTeX source of the formulas on this page

\[ 3x - 5 = 40\ \Rightarrow\ x = 15 \]
\[ 3x - 5 = 40 \]
\[ 3x - 5 + 5 = 40 + 5 \ \Rightarrow\ 3x = 45 \]
\[ \frac{3x}{3} = \frac{45}{3} \ \Rightarrow\ x = 15 \]
\[ 3\cdot15 - 5 = 45 - 5 = 40 \checkmark \]

Trying values of x in 3x − 5 = 40

x	3x − 5	Equals 40?
13	34	no
14	37	no
15	40	yes
16	43	no
17	46	no

Questions

What is x in 3x − 5 = 40?

The solution of 3x − 5 = 40 is x = 15.

How do you solve 3x − 5 = 40?

Add 5 to both sides to get 3x = 45, then divide both sides by 3 to get x = 15.

How do I check the answer?

Replace x by 15: 3(15) − 5 = 40, which is 40.

Solve 3x − 5 = 40

How to work it out

Trying values of x in 3x − 5 = 40

Questions

Similar equations