AMC 8 L1: Calculation Tricks

Complete problem set with solutions and individual problem pages

Problem 14 Easy

Suppose that a*b means 3a-b. What is the value of x if 2*(5*x)=1? (2016 AMC8 Problem, Question #10)

  • A.

    \frac{1}{10}

  • B.

    2

  • C.

    \frac{10}{3}

  • D.

    10

  • E.

    14

Answer:D
Solution

Suppose 5*x=y, then 2*y=3\times 2-y=1\Rightarrowy=5.

So 5*x=5, 5\times 3-x=5\Rightarrowx=10.

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