Question 1162488
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Let the 4th term be x, and let the common difference be d.  Then<br>
{{{x/(x+3d) = 2/3}}}
{{{2(x+3d) = 3x}}}
{{{2x+6d = 3x}}}
{{{x = 6d}}}<br>
Then<br>
{{{a6/a8 = (x+2d)/(x+4d) = (6d+2d)/(6d+4d) = (8d)/(10d) = 4/5}}}<br>