Why is subtracting mixed numbers sometimes more complicated than adding them?

Subtraction does not have the commutative property, and you sometimes need to borrow from the whole number.

What is the first step you should take when subtracting mixed numbers with unlike denominators?

Change the fractions to have like denominators.

Borrowing involves reducing the whole number by 1 and adding that 1 (as a whole fraction) to the existing fraction.

I can subtract mixed numbers with unlike denominators.

1
When subtracting mixed numbers, it is important to subtract the entire mixed number, including both the whole number and fraction parts.
2
When subtracting mixed numbers in stacked form, if the top fraction is smaller than the bottom fraction, you need to borrow or re-group from the whole number.
3
When borrowing, you can change the whole number part into a whole fraction such as changing 1 into 3/3, 5/5, or 8/8 to help make the top fraction bigger.