<span>The full arc of the circumference is:</span>
<span> S = 2pi * r</span>
<span> The arch is:</span>
<span> S '= (3/5) pi * r</span>
<span> Dividing we have:</span>
<span> S '/ S = ((3/5) pi * r) / (2pi * r)</span>
<span> Simplifying we have:</span>
<span> S '/ S = ((3/5)) / (2)</span>
<span> S '/ S = ((3/10))</span>
<span> Answer:</span>
<span> The fraction of the arch is:</span>
<span><span> S '/ S = ((3/10))</span></span>