Плиззззз решите (?!??

Question

Плиззззз решите (?!??

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Answer 1

2/5 + (3/5 - 2/7) : (1/4 + 1/7) = 2/5 + (21/35-14/35) : (7/28 + 4/28)=

2/5 + 7/35 : 11/28 = 2/5 + 7/35 * 28/11 =2/5 + 1/5 * 28/11 = 2/5 + 28/55 = 22/55 + 28/55 = 50/55 = 10/11