Predict the result
Add seven and two thirds to five and four sevenths.

Set up the model
Combine the whole-number parts.
Use twenty one as the common denominator for the fractions.

Work the example
The fractional parts total twenty six twenty firsts, which includes one extra whole.
The sum is thirteen and five twenty firsts.

Check the result
Subtract three and five fourteenths from eight and two sevenths.
Take eight seconds to think before the answer appears.
[Eight-second silent pause to work; the answer remains hidden.]
After borrowing one whole, the result is four and thirteen fourteenths.

Interpret the result
Borrowing one whole changes its form into fractional pieces without changing the value.