Question

am I doing this equation correctly, please help.

K3PO4(aq) + Ba(NO3)2(aq)

my answer: 3K(NO3)2(aq) + 2Ba(PO4)3(s) Double displacement
precipitation

Answer 1

Double displacement is right.
The equation is wrong. Your error in the equation is that you have tried to balance the equations by making the products fit the balanced numbers you need. It doesn't work that way. Here is what you do.
The product will be K and NO3 for one and Ba and PO4 as the other.

K is valence of +1, NO3 has valence of -1 so the formula is KNO3.

Ba is +2 and PO4 is -3 so the formula for barium phosphate is Ba3(PO4)2. After you have that you balance the equation.
K3PO4 + Ba(NO3)2 ==> Ba3(PO4)2 + KNO3. Then you balance remembering this ONE RULE. YOU MAY NOT CHANGE THE SUBSCRIPTS; YOU MAY CHANGE ONLY THE COEFFICIENTS.
Post your work if you want me to check it.