I am trying to figuare out my ridge peak height, mean height, and eave height. My walls are 12 ft 8 inches tall, my roof is 4/12 pitch, the width of building is 40ft and the overhang is 22 1/2 inches. Can anyone help me? Thanks

Your ridge height should be 6'8" or a total level ground to ridge top 19'4".
Your eave height can be anywhere from 12'8" to 12' depending on your overhang design. Truss w/ level bottom cord or stick framed rafter.
Your mean height roof height should be about 16'. I could be wrong on this. Can't read my own hand writing trying to interpret the formula I have written down.