Question

what is the total number of atoms in the compound (NH4)3PO4?

Answer 1

Pick a number. Any number you choose will be correct because you didn't specify how much (NH3)3PO4 you have. I assume you means for 1 molecule. There are 3N, 9H, 1P and 4O for a total of 17 per molecule.

Answer 2

(NH4)3PO4

=
Nitrogen = 3
Hydrogen = 4x3 (12)
Phosphorus = 1
Oxygen = 4
3+12+1+4=20

the answer is there are 20 atoms

Answer 3

Worng

Answer 4

20