Determining Supply from a Value Scale (hint)

Smith owns three cows. If he were to add another to his stock, therefore, it would serve as his fourth cow. What is the highest price that would have less utility to Smith than a fourth cow?

Smith      26 hens      1st cow      25 hens      24 hens      23 hens      2nd cow      22 hens        . . .      19 hens      3rd cow      18 hens        . . .      12 hens      4th cow      11 hens      10 hens      9 hens      5th cow      8 hens        . . .      5 hens      6th cow      4 hens      7th cow      8th cow      3 hens      9th cow      2 hens      10th cow      1 hens      11th cow        . . .   stock:  3 cows, 100 hens