Heya!!
For calculate aceleration, lets applicate second law of Newton:

Δ Being Δ
F = Force = 85,5 N
m = Mass = 24,3 kg
a = Aceleration = ?
⇒ Let's replace according the formula and clear "a":

⇒ Resolving

Result:
The aceleration is 3,41 meters per second squared (m/s²)
Good Luck!!