The master and the apprentice processed a batch of parts. The apprentice finished 40% of the total, and the master processed 240 parts. How many parts are there in total? (solution of a series of equations)

The master and the apprentice processed a batch of parts. The apprentice finished 40% of the total, and the master processed 240 parts. How many parts are there in total? (solution of a series of equations)


Suppose there are x parts in this batch, then
X*(1-40%)=240
The solution is x = 400
A: there are 400 parts in this batch