Answer
$$T=\frac{\sqrt{x^2+4}}{2}+\frac{\sqrt{x^2-6x+10}}{4}$$
Work Step by Step
As we know, the time needed to travel $\Delta x$ at the speed $v$ is $\Delta T = \frac{\Delta x}{v}$. So, the only things needed to be calculated are the distance $\Delta x_1$ traveled by rowing and the distance $\Delta x_2$ traveled by walking.
According to the figure, by applying the Pythagorean Theorem we obtain$$\Delta x_1=\sqrt{x^2+2^2}= \sqrt{x^2+4} \\ \Delta x_2= \sqrt{(3-x)^2+1^2}= \sqrt{x^2-6x+10} \, .$$Thus, the total time of the trip is$$T=\Delta T_1+\Delta T_2=\frac{\Delta x_1}{v_1}+ \frac{\Delta x_2}{v_2}= \frac{\sqrt{x^2+4}}{2}+\frac{\sqrt{x^2-6x+10}}{4} \, .$$
