Ok
6+1=7
if only we could find 1
hmm
4+1=5
so mark a starting line
put the 4 inch and 5 inch wood at that line, facing the same direction (lying flat on paper)
the difference between the pieces of wood is 1 inch
mark the end of the 5 inch and the end of the 4 inch
that is 1 inch
now pick either end of that 1 inch mark and measure 6 inches more
6+1=7
if only we could find 1
hmm
4+1=5
so mark a starting line
put the 4 inch and 5 inch wood at that line, facing the same direction (lying flat on paper)
the difference between the pieces of wood is 1 inch
mark the end of the 5 inch and the end of the 4 inch
that is 1 inch
now pick either end of that 1 inch mark and measure 6 inches more