#### Answer

The number is $10$.

#### Work Step by Step

First, let's translate this statement into an algebraic equation we can solve. Let's first break it into its component parts.
"$6$ times a number" is $6x$.
"Decreased by $20$" means to subtract $20$.
"Is $4$ times the number" means $ = 4x$.
Now, let's put the components together to make an equation:
$$6x - 20 = 4x$$
Add $20$ to each side to move the constant to one side of the equation:
$$6x = 4x + 20$$
Subtract $4x$ from each side to isolate variables to the other side of the equation:
$$2x = 20$$
Divide both sides by $2$ to solve for $x$:
$$x = 10$$
The number is $10$.