To know how many bowls she can create, we have to find the maximum common factor between 15 and 30.
[tex]\begin{gathered} 15=5\cdot3 \\ 30=5\cdot3\cdot2 \\ mcf=5\cdot3=15 \end{gathered}[/tex]This maximum common factor is 15, so each bowl will have 15/15=1 walnut and 30/15=2 cashews.
Answer: 15 bowls.