[tex]ribbon \: b \\ = \frac{1}{3} + \frac{2}{5} \\ = \frac{5}{15} + \frac{6}{15} \\ = \frac{11}{15} yds[/tex]
[tex]ribbon \: a + b \\ = \frac{11}{15} + \frac{1}{3} \\ = \frac{11}{15} + \frac{5}{15} \\ = \frac{16}{15} \\ = 1 \frac{1}{15} yds \: in \: total[/tex]