2020 AMC 12A Problems/Problem 1

Problem

Carlos took $70\%$ of a whole pie. Maria took one third of the remainder. What portion of the whole pie was left?

$\textbf{(A)}\ 10\%\qquad\textbf{(B)}\ 15\%\qquad\textbf{(C)}\ 20\%\qquad\textbf{(D)}\ 30\%\qquad\textbf{(E)}\ 35\%$

If Carlos took 70% of the pie, 30% must be remaining. After Maria takes 1/3 of the remaining 30%, meaning that 2/3 is left.

Therefore:

(3 / 10) * (2 / 3) = (2 / 10) = 20%

2020 AMC 12A (Problems • Answer Key • Resources)
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