Answer:
He should have multiplied both numbers by 100
Step-by-step explanation:
Given
See Attachment for given
Required
What's Chen error
Chen error is at step 2 where he changed 0.9 to 9.
Any changes made on the divisor must also be made on the dividend
He got 9 by multiplying 0.9 by 10;
So, his mistake is that he should have multiplied both numbers by the same number.
From the list of given options, the option that best answer this question is He should have multiplied both numbers by 100
