Answer 1: He had 21 pesos
Answer 2: 27 patatoes was served
1/3 of 27 = 9
9 was for each farmers
The first eat 9 potatoes
Remainder 27 - 9 =18
The second eat 1/3 of the remaining
1/3 of 18 =6
Remaining 18-6 =12
1/3 of the remainder from farmer 2
1/3 of 12 =4.
The suppose to eat 9 each so
Famer 1 will eat nothing =0
Farmer 2 eat 6 out of 9 (9-6)=3
Farmer 3 eats 4 out of 9 (9-4)=5
I invite @roshanee , @mubdi-technology