The girl is 9 years old, 135, weighing 50. What size shoes does she wear?

Generalized Young's Law for centimeter conversion of China's ordinary shoe size:

The formula for finding the shoe size: size = cm× 2- 10, that is, finding the shoe size when the foot length is known: the foot length is 24 cm× 2- 10 = 38 yards);

The formula for finding the foot length: cm = (code+10)÷2, that is, finding the foot length for the known shoe size: (code 38+10)÷2= foot length 24cm).

Remarks: This centimeter refers to the empty length of shoes.

If it's too much trouble, go to a physical store to buy shoes. If many shoes are not standard sizes, it is actually difficult to determine the size.