The area of a rectangle is 360 Sq.m. If its length is increased by 10m and its width is decreased by 6m, then its area does not change. Find the perimeter of the original rectangle.	Choose the correct option.
A) 74 m
B) 75 m
C) 76 m
D) 77 m
E) 78 m

Rationale: let l and b are the length and width of the original rectangle . since , l * b = 360 sq . m - ( 1 ) now , a / c to the problem ( l + 10 ) * ( b - 6 ) = 360 sq . m therefore , b = 6 ( 1 + l / 10 ) - ( 2 ) l * l + 10 l - 600 = 0 { by using equations 1 and 2 } thereafter , ( l - 20 ) ( l + 30 ) = 0 hence , l = 20 m b = 18 m { by using equation 2 } now , perimeter of the original rectangle = 2 ( l + b ) = 2 ( 20 + 18 ) = 76 m answer : c
Answer: C