3." Again, a similar method is used, with 45 as the common multiplier, yielding 1/9 + 1/40 as the answer" quote from Robins-Shute.
Translating RMP 23's intermediate calculation and answer requires the use of LCM 360, a point mentioned by Franz, but in a context that does not coincide with Ahmes' LCM 45 proof. To parse Ahmes' proof, let's follow every step as was done in RMP 66 (yesterday on the Math forum).
4. Another summary of RMP 23, taken from my Ahmes Papyrus blog says:
An concise analysis is required to follow Ahmes' precise proof steps. I did not do that, nor did Franz, per:
"Proportional adding up is the arithmetic method of the Rhind Mathematical Papyrus. I explained it at length in the case of RMP 66. Now let me demonstrate it also in the case of RMP 23 whose working is only partly rendered.