Explanation:
Length = 3 + w <=======given
area of a rectangle = L * w = 30 m ^2
(3+w) * w = 30 expand
3w + w ^2- 30 = 0 rearrange
w^2 + 3w -30 = 0 Use Quadratic Formula a = 1 b = 3 c = 3
to find w = 4.179 m then L = 4.179 + 3 = 7.179 m
Round as needed !