Solve 7x − 5 = 128

The solution of 7x − 5 = 128 is x = 19.

7x - 5 = 128\ \Rightarrow\ x = 19

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

The lines y = 7x − 5 and y = 128 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.
$7x - 5 = 128$
2
Add 5 to both sides:
$7x - 5 + 5 = 128 + 5 \ \Rightarrow\ 7x = 133$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{133}{7} \ \Rightarrow\ x = 19$
4
Check: put x = 19 back into the equation.
$7\cdot19 - 5 = 133 - 5 = 128 \checkmark$

LaTeX source of the formulas on this page

\[ 7x - 5 = 128\ \Rightarrow\ x = 19 \]
\[ 7x - 5 = 128 \]
\[ 7x - 5 + 5 = 128 + 5 \ \Rightarrow\ 7x = 133 \]
\[ \frac{7x}{7} = \frac{133}{7} \ \Rightarrow\ x = 19 \]
\[ 7\cdot19 - 5 = 133 - 5 = 128 \checkmark \]

Trying values of x in 7x − 5 = 128

x	7x − 5	Equals 128?
17	114	no
18	121	no
19	128	yes
20	135	no
21	142	no

Questions

What is x in 7x − 5 = 128?

The solution of 7x − 5 = 128 is x = 19.

How do you solve 7x − 5 = 128?

Add 5 to both sides to get 7x = 133, then divide both sides by 7 to get x = 19.

How do I check the answer?

Replace x by 19: 7(19) − 5 = 128, which is 128.

Solve 7x − 5 = 128

How to work it out

Trying values of x in 7x − 5 = 128

Questions

Similar equations