Mike you can do this by selecting the node edit tool (below the pointer/selector tool) click on the red line and click the node you want to move. Just move the node of the red line up to meet the end of your longer blue line. This will change the angle of the red line though. You can click/drag select both nodes of the line and move it without changing the angle. Right click on a node for additional options.

You can also keep the same angle on the red line by just selecting the red line only, using the pointer/selection tool and click/drag it upwards to meet the top of your blue line. If you hold down the Ctrl key before you drag the red line, it will constrain it to move on a horizontal or vertical plane. If the red line is grouped with the blue line, ungroup first.

If you want to move the blue and the top red line together as one object, group them first. Don't include the bottom red line in the group.