To multiply two fractions, you multiply the numbers straight across. The numerators stick together and multiply; the denominators stick together and multiply. For example:
1/2 times 3/4 = (1 times 3)/(2 times 4) = 3/8
After multiplying, we reduce if possible. In this case, we cannot reduce, so we're done with this example.
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To divide two fractions, you would flip the second fraction and then multiply straight across. So, for example,
5/7 divided by 7/8 = (5/7) times (8/7) = (5 times 8)/(7 times 7) = 40/49
Notice how the steps are similar as before. The only difference really is that we flipped the second fraction.