Challenge for the smart

𝐶 + 𝐿 = 830. C+L=830.
From the two half-filled containers: each has 0.5 𝐿, so together the liquids sum to  L. The weight equation is:
2 𝐶 + 0.5 𝐿 + 0.5 𝐿 = 2 𝐶 + 𝐿 = 960.
 Substitute 𝐿 L from the first equation into the second. From (1): 𝐿 = 830 − 𝐶 . L=830−C. Put that into (2):
2 𝐶 + ( 830 − 𝐶 ) = 960.
Simplify:
2 𝐶 + 830 − 𝐶 = 960 ⇒ 𝐶 + 830 = 960. 2C+830−C=960⇒C+830=960. So 𝐶 = 960 − 830 = 130.
(Optional check) If 𝐶 = 130 C=130, then 𝐿 = 830 − 130 = 700.
 Two half containers:
2 𝐶 + 𝐿 = 2 ⋅ 130 = 260 + 700 = 960 2C+L=2⋅130=260+700=960 ✓
Final answer
The mass of the empty container is 130 g.
Little congratulation (for anyone who guessed it already)
If you guessed 130 g before seeing the solution — well done! 🎉 That was a smart move — excellent intuition and great reasoning skills! 👏