simplify the following by rearranging 625 x 48 x 16 x 5

Question : Simplify the following equation. What is the difference between the two values of $x$?
$7 x+4\left\{x^2 \div(5 x \div 10)\right\}-3\left\{5 \frac{1}{3}-x^3 \div\left(3 x^2 \div x\right)\right\}=0$

Option 1: 8

Option 2: 16

Option 3: 5

Option 4: 17

Question : Simplify: $\frac{256 x^4-16 y^4}{\left(80 x^2-20 y^2\right)\left(16 x^2+4 y^2\right)}$

Option 1: $5$

Option 2: $\frac{1}{20}$

Option 3: $\frac{1}{5}$

Option 4: $\frac{2}{5}$

Question : Simplify the following expression.
$\{[(x-5)(x-1)]-[(9 x-5)(9x-1)]\} \div 16x$

Option 1: $2x(5x-3)$

Option 2: $-(5x-3)$

Option 3: $x(5x-3)$

Option 4: $-6x(5x-3)$