This is how we add


Step 1We still have different denominators (bottom numbers), though, so we need to get a common denominator. This will make the bottom numbers match. Multiply the denominators together first. Now, multiply each numerator by the other term's denominator. Now we multiply 1 by 7, and get 7, then we multiply 5 by 7 and get 35. Now for the second term. You multiply 4 by 5, and get 20, then multiply 5 by 7 and get 35. This gives us a new problem that looks like so:


Step 2Since our denominators match, we can add the numerators. 7 + 20 = 27 That gives us an answer of


Step 3Can this fraction be reduced? First, we attempt to divide it by 2... No good. So next you try the next prime number, which is 3... No good. So next you try the next prime number, which is 5... No good. So next you try the next prime number, which is 7... No good. So next you try the next prime number, which is 11... No good. So next you try the next prime number, which is 13... No good. So next you try the next prime number, which is 17... No good. So next you try the next prime number, which is 19... No good. So next you try the next prime number, which is 23... No good. So next you try the next prime number, which is 29... No good. 29 is larger than 27. So we're done reducing. And we're done! Here's the final answer to 1/5 + 4/7
