In order to find these out we need to report:
What skill was used?
What level was the skill and how much damage does the tooltip say?
How much damage it did?
What is the target's Armor and Resist (both in case phy. dmg. or mag dmg. isn't clear)?
If there was a Hades, Prometheus, Atalanta, Aphrodite, Hermes, Ion, or Echidna in battle; what level is their passive at and how much do those passives add?
How much MAG ATK and PHY ATK does the attacker have?
Once I get these numbers, I can solve for X, for example using made up numbers:
A team of Ion, Hercules, Atalanta, Aphrodite and Hermes fight mysteryman in Arena. Atlanta's frost shot does 3000 damage to enemy Hercules.
Frost shot is at skill level 75; which adds 500 more damage
Ion's passive reduces 6%
Hermes' passive adds 50 PHY ATK
Atalanta's passive adds 200 agility
Aphrodite's passive reduces enemy armor by 30
Hercules has 200 armor
Atalanta has 2000 PHY ATK
So we need to calculate final stats during battle in order to figure out how much damage frost shot derives from Atalanta's PHY ATK. Agility provides 0.1 armor and 1.4 PHY ATK per point. In battle, Atalanta has 2330 PHY ATK and enemy Hercules has (200-30+(0.1*200))=190 Armor.
The formula for reduction from a physical attack with x armor is: 0.242*ln(190) - 0.6484 = 0.6214 which is a 62.14% reduction.
This leads to the equation: 94 percent of the quantity of reduction ratio times the quantity of 2330 PHY ATK times X plus the flat 500 damage from frost shot equals 3000 physical damage.
0.94[0.6214(2330 x + 500)] = 3000
x = 1.990 ≈ 2
In this virtual situation, each point of physical attack (PHY ATK) contributes 2 points of damage for Atlanta's Frost Shot on the enemy Hercules.
FINAL ANSWER: X=2
PHY ATK RATIO FOR FROST SHOT: 2
200% of PHY ATK BECOMES DAMAGE IN FROST SHOT
NB: This situation is made up as an example how physical attack and magic attack ratios are calculated