For this task, we used the content aware fill and scale to resize the image. First of all, we expanded the canvas on one side so that there was a blank area to work with.
Content aware fill
First, we selected the blank area, with an overlap onto the image. Then we used the fill dialogue (Shift + Delete) to fill the area with pixels based on the overlap.
Content aware scale
First, we selected the image (Cmd + Click on the layer), then we used the content-aware scale tool to rescale the image.