If one holding Both Ascott and Ascendas HT, May I ask how do you calculate your new Ascott price per unit after merger with Ascendas HT?

Just take the number of units of Ascott offered multiply it by the current share price of Ascott, minus cash given and then divide it by the number of units of Ascott offered

i.e. if you have 1000 AHT shares

1000 AHT x 0.0543 = $54.30

794 AHBT * $1.30 = $1032.20

$1032.20 - $54.30 = $977.9

$977.9 / 794 = $1.23

Thus, if Ascott falls below $1.23, it'd be more worth it to sell off your AHT shares in the market