The idea
A fraction’s denominator names the size of the parts, and its numerator counts them. When the denominators match, the parts are already the same size. Add or subtract the counts while keeping that shared unit.
Before you begin: Recognise a numerator and denominator, and find simple equivalent fractions.
Add these fractions of the same-sized whole.
Both fractions count eighths. Imagine one whole split into eight equal parts.
Three eighths plus two eighths gives five eighths. The size of each part has not changed.
Five and eight have no shared factor greater than one, so this is simplest form. Five eighths is less than one whole.
A mistake to avoid
Do not add the denominators. If both amounts use eighths of the same-sized whole, the answer still counts eighths.
Your turn.
Subtract, then simplify.
Show the solution
Remove three tenths from seven tenths. Divide the remaining numerator and denominator by two.