Four-sevenths plus five-sevenths equals what?
We need to add four-sevenths and five-sevenths. How many sevenths do we have altogether? Nine-sevenths. Four plus five is nine. The denominator hasn’t changed. We’re adding sevenths to sevenths. Nine-sevenths is the correct answer.
But it’s also an improper fraction. It just means that the numerator is greater than the denominator. We could simplify this fraction. If we add three-sevenths to four-sevenths, we can see that four-sevenths and five-sevenths makes one whole plus two-sevenths. One and two-sevenths is also a correct answer. Four-sevenths plus five-sevenths equals nine-sevenths, which is the same as one and two-sevenths.