Simplify the following text for a Grade 5 native English-speaking person.
Original: In the Rig-Veda ( 6.61.7 ) Sarasvati is credited with killing the three-headed Vritra also known as Ahi ( `` snake '' ) .
Simplified: In the Rig-Veda ( 6.61.7 ) Sarasvati killed the three-headed snake , also known as Vritra .