Let's first distribute and simplify both sides of the equation:

(5a-1)(4-x)
= 5a(4) - 5a(x) - 1(4) + 1(x)
= 20a - 5a^2 - 4 + x

(x-2)(2-5x)
= x(2) - x(5x) - 2(2) + 2(5x)
= 2x - 5x^2 - 4 + 10x

Now, we can set the two expressions equal to each other:

20a - 5a^2 - 4 + x = 2x - 5x^2 - 4 + 10x

Next, simplify by combining like terms:

20a - 5a^2 - 4 + x = 2x - 5x^2 - 4 + 10x
20a - 5a^2 - 4 + x = 12x - 5x^2 - 4

Rearrange the terms to set the equation equal to zero:

5a^2 - 20a + 12x + 5x^2 - 13x = 0

Combine like terms:

5a^2 - 20a + 5x^2 - x = 0

Therefore, the final simplified equation is:

5a^2 - 20a + 5x^2 - x = 0