[latex]^{3/} \frac{4}{5} + ^{5/}\frac{1}{3} (same...demominator)= \frac{3*4}{3*5} +\frac{5*1}{5*3} = \frac{12}{15} + \frac{5}{15}= \frac{17}{15} [/latex]

4/5 + 1/3 = 12/15 + 5/15 = 17/15