Here's how to subtract 64/17 from 2/13:
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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 2 by 17, and get 34. Then we multiply 64 by 13, and get 832. Next we give both terms new denominators -- 13 × 17 = 221. So now our fractions look like this:
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Step 2Since our denominators match, we can subtract the numerators. 34 − 832 = -798 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... Nope! So now we try the next greatest prime number, 163... Nope! So now we try the next greatest prime number, 167... Nope! So now we try the next greatest prime number, 173... Nope! So now we try the next greatest prime number, 179... Nope! So now we try the next greatest prime number, 181... Nope! So now we try the next greatest prime number, 191... Nope! So now we try the next greatest prime number, 193... Nope! So now we try the next greatest prime number, 197... Nope! So now we try the next greatest prime number, 199... Nope! So now we try the next greatest prime number, 211... Nope! So now we try the next greatest prime number, 223... No good. 223 is larger than 221. So we're done reducing. There you have it! The final answer is:
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