15
Extractio de \({7 \over 10}\) de \({5 \over 6}\)
Verum si \({7 \over 10}\) de \({5 \over 6}\) extrahere volueris, reperies prescripta 21 et 25 et extrahe 21 de 25: remanent 4, que divide per 30 vel per ipsorum regulam, que est \({1~~0\phantom{0} \over 3~~10}\): exibit
30 \({1~~1\phantom{0} \over 3~~10}\) pro residuo quesite extractionis. Et si \({5 \over 6}\) per \({7 \over 10}\) dividere vis, divide 25 per 21; exibit
31 \({1~~1 \over 3~~7}\) 1. Et si \({7 \over 10}\) vis dividere per \({5 \over 6}\)
32, divide 21 per 25; exibunt \({1~~4 \over 5~~5}\).
