Hi Amanda,
Let W = the width and let L = length.
Area = length x width--> 308 = LW
The width is 3 meters longer than 1/2 of the length--> W = 3 + (L/2)
Substitute 3 + (L/2) for W in the area equation--> 308 = L (3 +(L/2))
308 = 3L + (L^2/2)
Multiply everything by 2 to get rid of the fraction--> 616 = 6L + L^2
Subtract 616 from both sides--> L^2 + 6L - 616 = 0
Quadratic equation: a=1 b=6 c= - 616
L = (-6 +/- sq root (36 + 2464)) / 2
L = -3 + 25 L = -3 -25 which you can forget about because you can't have a negative length.
So L = 22 meters
Then W = 14 meters
Dan