Create a cube, stretch it on X, rotate it 45° on X, cut it in half and mirror with a Mirror modifier:

Select its end and in front view, use the Shear tool (AltCtrlShiftS) and in the Operator box choose Offset > 1:

Cut an horizontal edge with the knife tool K to activate, A to cut orthogonally, C to cut through, press Shift if it is supposed to be cut at its middle:

Extrude the bottom triangle on X:

To measure an edge, you can enable the MeasureIt addon. Select an edge then in the N panel > View > MeasureIt Tool, click on Show and clik on Segment. You can remove the display with the X buttons a bit below on the same panel:
