Question 204368
a/b=a/c*c/b = 1/3 * 7/5 = 7/15
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a/b/c,, a/b=7/15,,,and  b/c =5/7 or 15/21,,therefore a/b/c = 7/15/21
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look  at  it  as  a/b and  b/c ,,,7:15,,,and  15:21,,,or  7:15:21