Question

how is this supposed to be awensered

Answer 1

I think it's like this: 
6:5:3 is the same as A:B:C
so then it would go 
A:B:30
but if 3 turns to 30, then it would go
60:50:30.
The area of the top of the box would be 60x50, which is 300.
I hope this helps! (and that I did it right)