To find the sum of the expressions \( 4 - \frac{2}{3}b + \frac{1}{4}a \) and \( \frac{1}{2}a + \frac{1}{6}b - 7 \), we will combine like terms.
Let's first write both expressions clearly:
- \( 4 - \frac{2}{3}b + \frac{1}{4}a \)
- \( \frac{1}{2}a + \frac{1}{6}b - 7 \)
Now, we can combine these expressions:
\[ (4 - 7) + \left(\frac{1}{4}a + \frac{1}{2}a\right) + \left(-\frac{2}{3}b + \frac{1}{6}b\right) \]
Let’s simplify each component:
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Constant terms: \[ 4 - 7 = -3 \]
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For the \(a\) terms: \[ \frac{1}{4}a + \frac{1}{2}a = \frac{1}{4}a + \frac{2}{4}a = \frac{3}{4}a \]
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For the \(b\) terms: To combine \(-\frac{2}{3}b\) and \(\frac{1}{6}b\), we need a common denominator. The least common denominator of 3 and 6 is 6.
- Convert \(-\frac{2}{3}b\) to sixths: \[ -\frac{2}{3}b = -\frac{4}{6}b \]
- Now combine: \[ -\frac{4}{6}b + \frac{1}{6}b = -\frac{4 - 1}{6}b = -\frac{3}{6}b = -\frac{1}{2}b \]
Now, combine all simplified parts together:
\[ -\frac{3}{4} + \frac{3}{4}a - \frac{1}{2}b \]
Thus, the final combined expression is:
\[ \frac{3}{4}a - \frac{1}{2}b - 3 \]
So the simplified sum of the expressions is:
\[ \frac{3}{4}a - \frac{1}{2}b - 3 \]
None of the outlined answer choices match the final answer. Let’s double-check in questions or make corrections.