56 ft by 40 ft
If we let x represent the multiplier for the ratio, then the perimeter is ...
... 2 × (7x +5x) = 24x = 192 ft.
Dividing by 24 gives
... x = 8 ft.
The dimensions are 7 and 5 times this multiplier, or ...
... 7×8 ft = 56 ft . . . . by . . . . 5×8 ft = 40 ft