It is asking you to subtract one-third from seven-ninths.
Let's practise
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- Read the question and then read it again. What is it asking you to do?
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- The denominators are not the same for both fractions so you need to use equivalent fractions.
Look at the denominators. Nine is a multiple of three so you can use denominator 9 and show as the equivalent fraction 
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- Rewrite the question and then do the subtraction.
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- What is your answer? Can your fraction be simplified?
Check your working using the inverse.
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The answer is .
is in its simplest form.
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