Both sides are equal,
If we change one, they will still be equal if we change both in the exact same way.
Subtract bx from both sides to bring the x parts together.
X is common in ax-bx, so we write it as x(a-b).
It's like 5(3)-3(3)=(5-3)3 or 7(4)-2(4)=(7-2)4.
Now, divide both sides by (a-b).