Bunuel wrote:
Official Solution:
We cannot simplify the given expression very much, because the denominator (which is a sum, \(a + 3b\)) is not a factor of the numerator. If we really wanted to, we could split the numerator and write the expression as a sum:
\(\frac{4a}{(a + 3b)} + \frac{6b}{(a + 3b)} =\) ?
Or we could leave the question as is. Either way, be sure not to cancel any of the coefficients, because the denominator is a sum - we can’t simply cancel the 6 in the numerator with the 3 in the denominator, for instance.
Statement 1: INSUFFICIENT. This gives us a relationship between \(a\) and \(b\). However, if we use it to solve for one of the variables and then we substitute that expression into the question, we'll quickly see that we will not get a single number:
From the statement: \(a = 6 + 3b\).
Substitute into the original question:
\(\frac{4(6 + 3b) + 3b}{6 + 3b + 3b} =\) ?
We can stop here if we see that the denominator is \(6 + 6b\), which will not cancel with the numerator of the combined fraction (which equals \(24 + 15b\)).
Hello, I have a question on the posted solution of Statement 1. When we substitute \(a = 6 + 3b\) back into the original equation, why do we have
\(\frac{4(6 + 3b) + 3b}{6 + 3b + 3b}\) instead of \(\frac{4(6 + 3b) + 6b}{6 + 3b + 3b}\)? This would simplify to \(\frac{24 + 18b}{6 + 6b} =\frac{6(4 + 3b)}{6 + 6b}\) I don't think it changes the answer but wanted to make sure I wasn't missing something here.