It takes 12 minutes for Xiaoming to walk from home to the library. If you use the same speed, it only takes 9 minutes to walk from the library to the school, and the distance from the school to the library is 540 meters.

Calculate the formula according to the meaning of the question:

720÷ 12×9

=60×9

=540 meters

So the distance between the school and the library is 540 meters.

Division calculation:

A number divided by the product of several numbers can be divided by the factors in the product in turn. For example: 320÷(2×5×8)=320÷2÷5÷8=4.

The quotient of a number divided by two numbers is equal to the number divided by the divisor in the quotient and then multiplied by the divisor in the quotient. For example: 56÷(8÷4)=56÷8×4=28.