In certain area of rectangular plot, a water tank cover area of 6 × 6 square foot in middle of plot and remaining of plot area is grass field. And on its one of the corner a cow tied with √7 foot length rope and at second of corner a cow tied with 2√7 foot length rope. And both of cows graze all in its circumstance area. But still 90% area of plot is grass field than find the length of plot if ratio of length and breadth is 66 : 61 respectively.