Naturally whatever is greater will be called length and the smaller one will be called breadth.
Let original and breadth be L and (L-7) ==> Area = L(L-7).
With new dimensions of length and breadth,
length = (L-4) and breadth = (L-7) + 3 = (L- 4)
==> New area = (L-4)(L-4) = original rectangular area = L(L-7)
or L² - 8L +16 = L² - 7L OR 8L - 7L = 16 ==> L = 16,
==> length and breadth of original rectangle are 16 and 9 respectively.