Which formula represents strontium phosphate?
(1) srpo4 (3) sr2(po4)3
(2) sr3po8 (4) sr3(po4)2

Strontium has a charge of 2+ as an ion, and a charge of -3. So to get an equal charge, the least common multiple is 6, so you would need 3 Strontium ions and you would need 2 phosphate ions. Keep in mind that you have to multiply the entire ion, so you would need to have , NOT  because then you would only have 1 phosphorous, and that would not be phosphate anymore.
So the correct one is #4

Adozen is 12, and your needing to calculate the weight of one medium egg, so i would do 21/12=1.75 per egg, and check your answer by doing 1.75 * 12= 21 : ) : ): ): ): ) i hoped i

The answer is probably c. xylem