5/7*(21/20)+16/21:8/7
5/7 * (21/20 - 7/30) + 16/21 : 8/7 = 1 1/41) 21/20 - 7/30 = 63/60 - 14/60 = 49/602) 5/7 * 49/60 = 7/123) 16/21 : 8/7 = 16/21 * 7/8 = 2/34) 7/12 + 2/3 = 7/12 + 8/12 = 15/12 = 1 3/12 = 1 1/4
3/4+2/3=9/12+8/12=17/12=1 5/12
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