the answer
he chemical reaction CrF3+H3PO4 → CrPO4 + 3HF
the main formula is
when we observe a reaction as follow:
XY + ZT --------------- XT + YZ
this is classified as double replacement reactions, this means: two ionic compounds exchange ions, producing 2 new ionic compounds.
in our case we have CrF3+H3PO4 → CrPO4 + 3HF
so the classification is double-replacement reactions