Answers

2016-08-01T19:54:03+08:00
1/s+1/b=1/(7/2); s-small pipe; b-big pipe; 1/14+1/b=2/7; 7/14+7/b=2; x(14) 7+98/b=28; 7b+98=28b; 21b=98; b=98/21; -
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