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Is this solvable? I think not, I think something is missing.

Am i wrong?

If 4a + b = 3 then 20a + 5 = ? a. 15 b. 1/4 c. 4/3 d. 3/4 
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    @Doug: Feel free to change it! – 2012-04-17

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You are quite correct: something has to be missing. No matter what value you give $a$, there is a value of $b$ that makes the first equation true, so $20a+5$ is indeterminate.

From the answers given, it’s clear that the second expression was supposed to be $20a+5b$; since this is $5(4a+b)$, the intended correct answer must be $15$.

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    Ok thanks, That sounds about right. – 2012-04-17
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You got 1 equation with 2 unknowns and you're trying to find the first one (finding 20a+5 requires a). Therefore it's unsolvable.

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    Thanks!, thats what I thought. – 2012-04-17