Explain which is the better value for money

a) 250g of spread at $1.85, or

B) 500g of spread at $3.10, or

C) 1 kg of spread at $5.90,

The answer is C.

Step-by-step explanation:

To start off 250g is $1.85 and we want to get to 500g so if we add $1.85 with $1.85 we will get $3.70. This amount is more than the number if we bought just 500g once than if we bought 250g twice, because if we did, we would be paying more. But that's not all, if we add 500g with 500g we will get $6.20. That's more than the original price for 1 kg and if we multiply 250g 4 times than we get 7.4. So in all we would buy 1 kg.