What is 20/17 + 9/12?
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This is how you add
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Step 1Of course, you can't add two fractions if the denominators (bottom numbers) don't match. To get a common denominator, multiply the denominators together. Then we fix the numerators by multiplying each one by their other term's denominator. Now you multiply 20 by 12, and get 240, then we multiply 17 by 12 and get 204. Do the same for the second term. We multiply 9 by 17, and get 153, then multiply 17 by 12 and get 204. The problem now has new fractions to add:
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Step 2Since our denominators match, we can add the numerators. 240 + 153 = 393 This yields the answer
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Step 3The last step is to reduce the fraction if we can. To find out, we try dividing it by 2... Nope. Try the next prime number, 3... Are both the numerator and the denominator evenly divisible by 3? Yes! So we reduce it:
Now, try the same number again. Nope. Try the next prime number, 5... Nope. Try the next prime number, 7... Nope. Try the next prime number, 11... Nope. Try the next prime number, 13... Nope. Try the next prime number, 17... Nope. Try the next prime number, 19... Nope. Try the next prime number, 23... Nope. Try the next prime number, 29... Nope. Try the next prime number, 31... Nope. Try the next prime number, 37... Nope. Try the next prime number, 41... Nope. Try the next prime number, 43... Nope. Try the next prime number, 47... Nope. Try the next prime number, 53... Nope. Try the next prime number, 59... Nope. Try the next prime number, 61... Nope. Try the next prime number, 67... Nope. Try the next prime number, 71... No good. 71 is larger than 68. So we're done reducing. Congratulations! Here's your final answer to 20/17 + 9/12
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