Subject: mathqa
Question: in what ratio should a variety of rice costing rs . 6.5 per kg be mixed with another variety of rice costing rs . 8.75 per kg to obtain a mixture costing rs . 7.50 per kg ?
Option: 
A: 5 / 3
B: 5 / 4
C: 5 / 9
D: 5 / 6
Answer: B