Area = f(x) = (6+2x)(5+2x) = 4x^2 + 22x + 30 square meters

f(x) is a quadratic function, 2 degree polynomial

f(x) = 120 = 4x^2 + 22x +30

4x^2 + 22x -90 = 0

x= -22/8 + or - (1/8)sqr(22^2 +16(90))

x = -11/4 + or - (1/8)sqr(1924) = about 2.5 meters (ignore the negative square root) for area=120

Area of the walkway is 10x+12x + 4x^2 = area of pond = 6(5) = 30

4x^2 +22x -30 =0

x = -22/8 + or - (1/8)sqr(22^4(4)(30)) = -11/8 + (1/8)sqr964= about 1, rounded off to nearest integer

But it's slightly larger than 1, as 22(1)+4(1) = just 26 for the walkway area < 30 for the pond

It's slightly bigger than x=1.1 meters 22(1.1)+4(1.1)^2 = 29.04 square meters