When we prime factorise 33 750, we shall then arrive at the
factors: 10, 50, 90, 150, 250, 270, 450......
We shall then do a systematic list. (Refer to Table 1)
From the list, you can see that 250 cents and 270 cents
differ by 20 cents. The number of files, 135 files and 125 files, also differ by 10 files.
All these meet the requirements of the problem.
Thus, Mr. Sim paid $2.70 for a file and he bought 125 files.
Table 1:
