2 1/5 · 3 - (5/7 - 6/5) : 2 3/7 = 6 целых 4/5
1) 5/7 - 6/5 = 25/35 - 42/35 = - 17/35
2) - 17/35 : 2 3/7 = - 17/35 : 17/7 = - 17/35 · 7/17 = - 7/35 = - 1/5
3) 2 1/5 · 3 = 11/5 · 3 = 33/5 = 6 3/5
4) 6 3/5 - (-1/5) = 6 3/5 + 1/5 = 6 4/5
28 квадратов.
S квадрата = 7*4 = 28..
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52+52+1=105 целых решений