Difference between revisions of "2005 AMC 12B Problems/Problem 2"

(Solution)
(Problem)
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== Problem ==
 
== Problem ==
The equations <math>2x+7=3</math> and <math>bx-10=-2</math> have the same solution for <math>x</math>.  What is the value of <math>b</math>?
+
A positive number <math>x</math> has the property that <math>x\%</math> of <math>x</math> is <math>4</math>.  What is <math>x</math>?
  
 
<math>
 
<math>
\mathrm{(A)}\ -8     \qquad
+
\mathrm{(A)}\ 2     \qquad
\mathrm{(B)}\ -4      \qquad
+
\mathrm{(B)}\ 4      \qquad
\mathrm{(C)}\ -2     \qquad
+
\mathrm{(C)}\ 10     \qquad
\mathrm{(D)}\ 4     \qquad
+
\mathrm{(D)}\ 20     \qquad
\mathrm{(E)}\ 8
+
\mathrm{(E)}\ 40
 
</math>
 
</math>
  

Revision as of 21:08, 17 April 2009

Problem

A positive number $x$ has the property that $x\%$ of $x$ is $4$. What is $x$?

$\mathrm{(A)}\ 2      \qquad \mathrm{(B)}\ 4      \qquad \mathrm{(C)}\ 10      \qquad \mathrm{(D)}\ 20      \qquad \mathrm{(E)}\ 40$

Solution

$2x+7=3 \Rightarrow 2x = -4 \Rightarrow x = -2$.

$-2b-10=-2 \Rightarrow -2b = 8 \Rightarrow b = \boxed{-4}$.

See also