Solve 5x − 5 = 90

The solution of 5x − 5 = 90 is x = 19.

5x - 5 = 90\ \Rightarrow\ x = 19

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The lines y = 5x − 5 and y = 90 meet at x = 19. 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.
$5x - 5 = 90$
2
Add 5 to both sides:
$5x - 5 + 5 = 90 + 5 \ \Rightarrow\ 5x = 95$
3
Divide both sides by 5:
$\frac{5x}{5} = \frac{95}{5} \ \Rightarrow\ x = 19$
4
Check: put x = 19 back into the equation.
$5\cdot19 - 5 = 95 - 5 = 90 \checkmark$

LaTeX source of the formulas on this page

\[ 5x - 5 = 90\ \Rightarrow\ x = 19 \]
\[ 5x - 5 = 90 \]
\[ 5x - 5 + 5 = 90 + 5 \ \Rightarrow\ 5x = 95 \]
\[ \frac{5x}{5} = \frac{95}{5} \ \Rightarrow\ x = 19 \]
\[ 5\cdot19 - 5 = 95 - 5 = 90 \checkmark \]

Trying values of x in 5x − 5 = 90

x	5x − 5	Equals 90?
17	80	no
18	85	no
19	90	yes
20	95	no
21	100	no

Questions

What is x in 5x − 5 = 90?

The solution of 5x − 5 = 90 is x = 19.

How do you solve 5x − 5 = 90?

Add 5 to both sides to get 5x = 95, then divide both sides by 5 to get x = 19.

How do I check the answer?

Replace x by 19: 5(19) − 5 = 90, which is 90.

Solve 5x − 5 = 90

How to work it out

Trying values of x in 5x − 5 = 90

Questions

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