Work done in stretching a spring to x length is \\\\(W=\\dfrac{1}{2}kx^2\\\\)\\\\(\ herefore\\\\) Work one in stretching from \\\\(x_1\\\\) to \\\\(x_2\\\\) is proportional to \\\\(W \\propto x_2^2-x_1^2\\\\)hence \\\\(\\dfrac{W_{20,30}}{W_{10,20}}=\\dfrac{500}{300}\\\\)so, 10 to 20 takes less work when compared to 20 to 30.