Is there a simpler way of finding X?

X = random((Player.WeaponMinDmg - 10%),(Player.WeaponMaxDmg + 10%))

And is this how I remove/add 10 percent of the weapon damage?

Basically, I want to find minimum and maximum damage of the weapon, let's say 50 min and 80 max. Then I want the computer to minus 10% from the minimum and add 10% onto the maximum. Then I want the computer to randomly select between those two variables. So it would end up selecting a random number between 45 and 88, with these current values.

I know how to do the Math part I am just not sure how it translates into Construct 2 logic and so on.