You can now either 1) make these into fractions and subtract or 2) subtract the whole numbers and the fractions separately. Either method should give the same result.
1)
20 25/45 - 12 36/45
20 = 900/45 and 12 = 540/45 so:
7 34/45
2)
I want to subtract the 12 from the 20 and the two fractions separately. I can't subtract 36 from 25 without basically "borrowing" from the whole number like you would when doing long division.
20 25/45 - 12 36/45
19 45+25/45 - 12 36/45
19 70/45 - 12 36/45
19+70/45-12-36/45
19-12+70/45-36/45
7 34/45
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