A classic arithmetic problem written by Xie Chengze: 'There are chickens and rabbits in the same cage, with 35 heads and 94 feet in total. How many chickens and rabbits are there?' Su Qinghe solves it using symbolic representation similar to linear equations, finding 23 chickens and 12 rabbits. He later correctly solves a harder version with 218 heads and 676 legs.
