Answer:
Since the farmer wants to buy a 10 kg bag of fertilizer, he should buy it from merchant A. However, Merchant A and B are selling at the same price for a unit value. In other words, Both Merchant A and B are selling 1kg of dry fertilizer for $1.
Explanation:
Which merchant has the better deal means which merchant offers the farmer a better deal.
For Merchant A, 10 kg bag = $10
meaning it contains a real 10 kg bag of dry fertilizer which the farmer can use without losing any Kg to drying.
While for Merchant B, 10 kg bag = $8
where the 10kg = 80% dry fertilizer + 20% water content
But the farmer can only use the solid constituents of the bag which means,
Merchant B is giving 80/100 x 10Kg of dry fertilizer for $8
That is, 8kg for $8
Since the farmer wants to buy a 10 kg bag of fertilizer, he should buy it from merchant A. However, Merchant A and B are selling at the same price for a unit value. In other words, Both Merchant A and B are selling 1kg of dry fertilizer for $1.
