Solve 5x − 1 = 99

The solution of 5x − 1 = 99 is x = 20.

5x - 1 = 99\ \Rightarrow\ x = 20

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The lines y = 5x − 1 and y = 99 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.
$5x - 1 = 99$
2
Add 1 to both sides:
$5x - 1 + 1 = 99 + 1 \ \Rightarrow\ 5x = 100$
3
Divide both sides by 5:
$\frac{5x}{5} = \frac{100}{5} \ \Rightarrow\ x = 20$
4
Check: put x = 20 back into the equation.
$5\cdot20 - 1 = 100 - 1 = 99 \checkmark$

LaTeX source of the formulas on this page

\[ 5x - 1 = 99\ \Rightarrow\ x = 20 \]
\[ 5x - 1 = 99 \]
\[ 5x - 1 + 1 = 99 + 1 \ \Rightarrow\ 5x = 100 \]
\[ \frac{5x}{5} = \frac{100}{5} \ \Rightarrow\ x = 20 \]
\[ 5\cdot20 - 1 = 100 - 1 = 99 \checkmark \]

Trying values of x in 5x − 1 = 99

x	5x − 1	Equals 99?
18	89	no
19	94	no
20	99	yes
21	104	no
22	109	no

Questions

What is x in 5x − 1 = 99?

The solution of 5x − 1 = 99 is x = 20.

How do you solve 5x − 1 = 99?

Add 1 to both sides to get 5x = 100, then divide both sides by 5 to get x = 20.

How do I check the answer?

Replace x by 20: 5(20) − 1 = 99, which is 99.

Solve 5x − 1 = 99

How to work it out

Trying values of x in 5x − 1 = 99

Questions

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