Since GH is equal to EL, C,
while GH is equal to MN,
therefore MN is also equal to EL, C.
Let EL be subtracted from each;
therefore the remainder, the gnomon XWV, is equal to C.
Now, since AE is equal to EB,
AN is also equal to NB [I. 36], that is, to LP [I. 43].
Let EO be added to each;
therefore the whole AO is equal to the gnomon VWX.
But the gnomon VWX is equal to C;
therefore AO is also equal to C.