What is 3/20 + 4/9?
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Let's add
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Step 1We can't add two fractions with different denominators (the bottom number). So you need to get a common denominator - both bottom numbers need to match. To do this, you'll multiply the denominators times each other... but the numerators have to change, too. They get multiplied by the other term's denominator. So we multiply 3 by 9, and get 27, then we multiply 20 by 9 and get 180. Do the same for the second term. We multiply 4 by 20, and get 80, then multiply 20 by 9 and get 180. So now our fractions look like this:
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Step 2Since our denominators match, we can add the numerators. 27 + 80 = 107 Now we have an answer.
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Step 3Last of all, we need to simplify the fraction, if possible. Can it be reduced to a simpler fraction? To find out, we try dividing it by 2... Nope! So now we try the next greatest prime number, 3... Nope! So now we try the next greatest prime number, 5... Nope! So now we try the next greatest prime number, 7... Nope! So now we try the next greatest prime number, 11... Nope! So now we try the next greatest prime number, 13... Nope! So now we try the next greatest prime number, 17... Nope! So now we try the next greatest prime number, 19... Nope! So now we try the next greatest prime number, 23... Nope! So now we try the next greatest prime number, 29... Nope! So now we try the next greatest prime number, 31... Nope! So now we try the next greatest prime number, 37... Nope! So now we try the next greatest prime number, 41... Nope! So now we try the next greatest prime number, 43... Nope! So now we try the next greatest prime number, 47... Nope! So now we try the next greatest prime number, 53... Nope! So now we try the next greatest prime number, 59... Nope! So now we try the next greatest prime number, 61... Nope! So now we try the next greatest prime number, 67... Nope! So now we try the next greatest prime number, 71... Nope! So now we try the next greatest prime number, 73... Nope! So now we try the next greatest prime number, 79... Nope! So now we try the next greatest prime number, 83... Nope! So now we try the next greatest prime number, 89... Nope! So now we try the next greatest prime number, 97... Nope! So now we try the next greatest prime number, 101... Nope! So now we try the next greatest prime number, 103... Nope! So now we try the next greatest prime number, 107... Nope! So now we try the next greatest prime number, 109... No good. 109 is larger than 107. So we're done reducing. There you have it! Here's the final answer to 3/20 + 4/9
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