[caliaca]

That math is wrong once again. 3 per item with 200% is only 6, so 6 x 2 items is 12, with two hits is only 24 total. I am unsure why you are doubling it again. (Power 3x200%=6 power times 2 hits = 12 Power, times 2 accessries = 24 Total Power). Is my math missing something here?

3 per item. 
You have two accessories. 
Since you have two accessories, that's 3 * 2 elemental attack added.
You have a bonus 6 elemental attack. 

Thunder steps hits twice at 200%.
The first hit thus adds 12 damage. The second hit also adds 12 damage.
You can use thunder steps twice in one turn due to having 7 momentum 
Thus it's 12  +12 + 12 + 12 = 48

Edit: Adding on here, cause it's dancer and they have tempo and crit. If they have max tempo and crit, they'd actually gain around 75 damage a turn from this.