Can you please explain a little more i’m not fully understanding
So, dimensional analysis will help with this

Hope this helps!
Answer:
Dude the answer is 8!
Step-by-step explanation:
You literally multiply the two together. Come on man...
12+4+9+13+7+11+5+2+_+_ /10= 8
x10 both sides
12+4+9+13+7+11+5+2+_+_=80
63+_+_=80
-63 both sides
_+_= 17
any two numbers that add up to 17 can go in the planks
7,10