Answer:
In 3K2O3 - 6 K atoms, 9 O atoms
In 2H3NCH3Br - 12 H atoms, 2 N atoms, 2 C atoms, 2 Br atoms
In 4 Ar2CO3 - 8 Ar atoms, 4 C atoms, 12 O atoms
Explanation:
All you need to do is multiply the coefficient by the number of each atom in the compound. For example, H3NCH3Br has 1 nitrogen, 1 carbon, 1 bromine, and 6 hydrogens. If you have 2H3NCH3Br, just multiply all those numbers by 2.
