$3+\frac{8}{60}+\frac{30}{3600}=3+\frac{8\cdot 60}{60\cdot 60}+\frac{30}{3600}=3+\frac{480}{3600}+\frac{30}{3600}=3\frac{510}{3600}=3\frac{{\sout{51}}^{17}}{{\sout{360}}^{120}}=3\frac{17}{120}$