Answer & Solution

Area of Park = 60 × 40 = 2400 m2
Area of lawn = 2109 m2
So, the area of mid way path = 2400 - 2109 = 291
Area of mid way path = x($$l$$ + b - x)
x(60 + 40 - x) = 291
x(100 - x) = 291
Now you can choose from option or solve in detail.
x2 - 100x + 291 = 0
x2 - (97 + 3)x + 291 = 0
x2 - 97x - 3x + 291 = 0
x(x - 97) - 3(x - 97) = 0
(x - 3)(x - 97) = 0
If x - 3 = 0
x = 3 m