Solve the Fraction Expression: 2/7 + 1/2 - 7/14

To solve the expression $\frac{2}{7}+\frac{1}{2}-\frac{7}{14}$, follow these steps:

• Step 1: Find the least common multiple (LCM) of the denominators 7, 2, and 14. The LCM is 14.
• Step 2: Convert each fraction to have the denominator of 14:
  $\frac{2}{7}$ becomes $\frac{2 \times 2}{7 \times 2} = \frac{4}{14}$
  $\frac{1}{2}$ becomes $\frac{1 \times 7}{2 \times 7} = \frac{7}{14}$
  $\frac{7}{14}$ remains $\frac{7}{14}$ since it's already over 14.
• Step 3: Perform the operations in the expression $\frac{4}{14} + \frac{7}{14} - \frac{7}{14}$:
  First, add $\frac{4}{14} + \frac{7}{14} = \frac{11}{14}$.
  Then, subtract $\frac{11}{14} - \frac{7}{14} = \frac{4}{14}$.
• Step 4: The result is already simplified. Thus, the solution to the problem is $\frac{4}{14}$.

Therefore, the solution to the problem is $\mathbf{\frac{4}{14}}$, which corresponds to choice $\mathbf{3}$.