Sounds like Andi might ill afford to go to the bookstore without pants!
"Tono is thinner than Andi, Andi is fatter than Tono." That's not correct punctuation in English. It should be a semicolon; it shouldn't be a comma.
Ummm "Tono is more thin than andi, andi is more fat than tono" should be accepted because its the equivalent statement and because it's the literal translation.