(a) It is given in the question that,

Cost of 5 kg wheat = Rs. 30.50

Therefore,

Cost of 1 kg wheat = = Rs. 6.10

Hence,

Cost of 8 kg wheat = 6.10 × 8 = Rs. 48.80

(b) It is given that,

Wheat purchased in Rs. 30.50 = 5 kg

Therefore,

Wheat purchased in Rs. 1 = kg

Hence,

Wheat purchased in Rs. 61 = × 61 = 10 kg