You only need a 2 at the end In front of the NaCl
Answer:
12.
1 + 2 + 1 = 4 + 1 + 2 + 1 + 4 = 12 = 4 + 1 + 2 + 1 + 4 = 1 + 2 + 1
Gravity is a force that can used draws everywhere, or everything to the Earth's center.
Hope it helped you.
-Charlie
Thanks!