Solve 10x − 9 = 191

The solution of 10x − 9 = 191 is x = 20.

10x - 9 = 191\ \Rightarrow\ x = 20

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

The lines y = 10x − 9 and y = 191 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.
$10x - 9 = 191$
2
Add 9 to both sides:
$10x - 9 + 9 = 191 + 9 \ \Rightarrow\ 10x = 200$
3
Divide both sides by 10:
$\frac{10x}{10} = \frac{200}{10} \ \Rightarrow\ x = 20$
4
Check: put x = 20 back into the equation.
$10\cdot20 - 9 = 200 - 9 = 191 \checkmark$

LaTeX source of the formulas on this page

\[ 10x - 9 = 191\ \Rightarrow\ x = 20 \]
\[ 10x - 9 = 191 \]
\[ 10x - 9 + 9 = 191 + 9 \ \Rightarrow\ 10x = 200 \]
\[ \frac{10x}{10} = \frac{200}{10} \ \Rightarrow\ x = 20 \]
\[ 10\cdot20 - 9 = 200 - 9 = 191 \checkmark \]

Trying values of x in 10x − 9 = 191

x	10x − 9	Equals 191?
18	171	no
19	181	no
20	191	yes
21	201	no
22	211	no

Questions

What is x in 10x − 9 = 191?

The solution of 10x − 9 = 191 is x = 20.

How do you solve 10x − 9 = 191?

Add 9 to both sides to get 10x = 200, then divide both sides by 10 to get x = 20.

How do I check the answer?

Replace x by 20: 10(20) − 9 = 191, which is 191.

Solve 10x − 9 = 191

How to work it out

Trying values of x in 10x − 9 = 191

Questions

Similar equations