Answer:
[tex](3 \: \: x) \binom{2x}{4} = (20) \\ (3 \times 2x) + (x \times 4) = (20)\\ 6x + 4x = 20 \\ 10x = 20 \\ x = \frac{20}{10} \\ \boxed{x = 2}[/tex]
