2005 AMC 10A Problems/Problem 3

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Problem

The equations $2x + 7 = 3$ and $bx - 10 = -2$ have the same solution $x$. What is the value of $b$?

$\mathrm{(A) \ } -8\qquad \mathrm{(B) \ } -4\qquad \mathrm{(C) \ } -2\qquad \mathrm{(D) \ } 4\qquad \mathrm{(E) \ } 8$

Solution

$2x + 7 = 3$

$x = -2$

$bx - 10 = -2$

$-2b - 10 = -2$

$b = -4 \Rightarrow B$

See Also