We have the following:
[tex]0.05\cdot n+$0.10\cdot d=$42.35[/tex]now, d = 3*n, therefore:
[tex]\begin{gathered} 0.05\cdot n+$0.10\cdot(3n)=$42.35 \\ 0.05n+0.3n=42.35 \\ n=\frac{42.35}{0.35} \\ n=121 \end{gathered}[/tex]therefore:
[tex]\begin{gathered} d=3\cdot121 \\ d=363 \end{gathered}[/tex]The answer is 121 nickels and 363 dimes
