What is 20/17 - 5/12?
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Here's how to subtract 5/12 from 20/17:
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Step 1We can't subtract two fractions with different denominators. So you need to get a common denominator. 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 20 by 12, and get 240. Then we multiply 5 by 17, and get 85. Next we give both terms new denominators -- 17 × 12 = 204. So now our fractions look like this:
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Step 2Since our denominators match, we can subtract the numerators. 240 − 85 = 155 So the answer is:
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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... Nope! So now we try the next greatest prime number, 113... Nope! So now we try the next greatest prime number, 127... Nope! So now we try the next greatest prime number, 131... Nope! So now we try the next greatest prime number, 137... Nope! So now we try the next greatest prime number, 139... Nope! So now we try the next greatest prime number, 149... Nope! So now we try the next greatest prime number, 151... Nope! So now we try the next greatest prime number, 157... No good. 157 is larger than 155. So we're done reducing. There you have it! The final answer is:
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