Surya Siddhanta
अजादिकेन्द्रे सर्वेषाम् *शैघ्र्ये मान्दे च कर्मणि /(C मान्दे शैघ्रे)। धनम् ग्रहाणाम् लिप्तादि तुलादाव् र्णम् एव च ॥
In the Śíghra and Manda operations, the (second or first) equation of a planet in minutes is to be additive when the (second or first) Kendra (of the planet) is less than 6 signs; but when it is greater than 6 signs, the (2nd or 1st) equation is to be subtractive.
english translation
ajAdikendre sarveSAm *zaighrye mAnde ca karmaNi /(C mAnde zaighre)। dhanam grahANAm liptAdi tulAdAv rNam eva ca ॥
hk transliteration by Sanscript