26*(21-у)*9=26*9*(21-у)=234*(21-у)=4914-234у
при у=14
4914-234*14=4914-3276=1638
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289÷17+х÷69=17+х÷69
при х=966
17+966÷69=17+14=31
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(у+63)*50-15
при у=7
(7+63)*50-15=70*50-15=3500-15=3485
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64-40+88-z=112-z
z=38
112-38=74
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87*5-8*y=435-8y
y=64
435-8*64=435-512=-77