No.
12/5 cannot be simplified.
It is: 12/20 = 3/5 simplified
1 over 12 is simplified
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One
It cannot be simplified. That is the simplest form of the fraction.
Twelve minus seven is five
12/16 = 3/4
It is 12/16, which can be simplified, if required.
Seven and five is twelve. If you say, 'seven and five are twelve', you are actually saying that the number 7 is 12, and the number 5 is 12, which is impossible.
One and seven eighths is in its lowest form and cannot be simplified.
The decimal for seven and twelve hundredths is 7.12