You only need to substitute the values in this transfer function.
P = ΔP1500 x PCODE + (100 – ΔP1500)
ΔP1500 = 2.750 kPa/count (Should be in the datasheet on pressure measurement characteristics)
PCODE = 0x20 = 32
P = 2.750 kpa/count x 32 count + (100 - 2.750 kPa/count)
P = 88 kPa + 97.25 kpa
P = 185.25 kPa
You can also refer to the attachment for more detail in the correspondence between compensated data in common units.