Basically, this is saying that 80% of (x) = 2 so you have know what the whole would be. It would be 2.5 because 80% of 2.5 is 2. So because you are subtracting 7 from v to get 2.5, you have to add 2.5 to 7 to get v. V=9.5
The area of a rectangular table is calculated by multiplying the length and width. It is also given that the length and width of the larger table is double the length and width of small table