$$1\frac{12}{14} + \frac{2}{14} = 1\frac{12+2}{14} = 1\frac{14}{14} = 1 + 1 = 2$$
$$5 - 2\frac{34}{43} = 4\frac{43}{43} - 2\frac{34}{43} = (4-2) + \frac{43-34}{43} = 2\frac{9}{43}$$
$$24\frac{12}{17} - 2\frac{13}{17} = 23\frac{17+12}{17} - 2\frac{13}{17} = 23\frac{29}{17} - 2\frac{13}{17} = (23-2) + \frac{29-13}{17} = 21\frac{16}{17}$$
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