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2020 AMC 12A Problem 1

Problem 1 of 25EasierAlgebra

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

Answer choices

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Solution

After Carlos takes 70%,70\%, the remaining portion is 30%.30\%. Maria takes one third of this, namely 13⋅30%=10%,\tfrac13 \cdot 30\% = 10\%, leaving 30%−10%=20%.30\% - 10\% = 20\%. Thus, C is the correct answer.

More practice

Concepts: percentage · fraction

Problem text and solution from the LIVE past-contest archive. See also the AoPS wiki page for community solutions.