Art of Problem Solving

2025 AMC 10A Problems/Problem 2

The following problem is from both the 2025 AMC 10A #2 and 2025 AMC 12A #2, so both problems redirect to this page.

Problem

A box contains $10$ pounds of a nut mix that is $50$ percent peanuts, $20$ percent cashews, and $30$ percent almonds. A second nut mix containing $20$ percent peanuts, $40$ percent cashews, and $40$ percent almonds is added to the box resulting in a new nut mix that is $40$ percent peanuts. How many pounds of cashews are now in the box?

$\textbf{(A)}~3.5\qquad\textbf{(B)}~4\qquad\textbf{(C)}~4.5\qquad\textbf{(D)}~5\qquad\textbf{(E)}~6$

Solution 1

\documentclass{article} \begin{document}

Since the first box had 5 pounds, and 50 percent off it had peanuts, we know there were 5 pounds of peanuts at the beginning. \\ Adding the second mixture of nuts, we call this value $x$, as in $x$ pounds. \\ Of that 20\% or $x/5$, are peanuts. \\ Since the final percentage in 40 percent peanuts, $(5 + x/5)/(10 + x) = 2/5$. \\ Multiplying both sides by 5, we get, $25 + x/10 + x = 2$. \\ Multiplying both sides by $10 + x$, we get $25 + x = 20 + 2x$. \\ This gives us $x = 5$. \\ But the problem is asking us to solve for cashews. \\ The first mixture was $1/5$ cashews, there were 2 cashews in the first mix. \\ In the second, there were $2x/5$ cashews, or 2 pounds of cashews. \\ Adding this together gives us a final total of $2 + 2 = \boxed{4}$ cashews.

\end{document} ~Minor edits to latex by WildSealVM/Vincent M.

See Also

2025 AMC 10A (ProblemsAnswer KeyResources)
Preceded by
Problem 1
Followed by
Problem 3
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AMC 10 Problems and Solutions
2025 AMC 12A (ProblemsAnswer KeyResources)
Preceded by
Problem 1
Followed by
Problem 3
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AMC 12 Problems and Solutions

These problems are copyrighted © by the Mathematical Association of America.