Solve 8x + 7 = 87

The solution of 8x + 7 = 87 is x = 10.

8x + 7 = 87\ \Rightarrow\ x = 10

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

The lines y = 8x + 7 and y = 87 meet at x = 10. 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 addition, then the multiplication.
$8x + 7 = 87$
2
Subtract 7 from both sides:
$8x + 7 - 7 = 87 - 7 \ \Rightarrow\ 8x = 80$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{80}{8} \ \Rightarrow\ x = 10$
4
Check: put x = 10 back into the equation.
$8\cdot10 + 7 = 80 + 7 = 87 \checkmark$

LaTeX source of the formulas on this page

\[ 8x + 7 = 87\ \Rightarrow\ x = 10 \]
\[ 8x + 7 = 87 \]
\[ 8x + 7 - 7 = 87 - 7 \ \Rightarrow\ 8x = 80 \]
\[ \frac{8x}{8} = \frac{80}{8} \ \Rightarrow\ x = 10 \]
\[ 8\cdot10 + 7 = 80 + 7 = 87 \checkmark \]

Trying values of x in 8x + 7 = 87

x	8x + 7	Equals 87?
8	71	no
9	79	no
10	87	yes
11	95	no
12	103	no

Questions

What is x in 8x + 7 = 87?

The solution of 8x + 7 = 87 is x = 10.

How do you solve 8x + 7 = 87?

Subtract 7 from both sides to get 8x = 80, then divide both sides by 8 to get x = 10.

How do I check the answer?

Replace x by 10: 8(10) + 7 = 87, which is 87.

Solve 8x + 7 = 87

How to work it out

Trying values of x in 8x + 7 = 87

Questions

Similar equations