To go from the equation \( 2x + 7y = 14 \) to the equivalent equation \( 4x + 14y = 28 \), you need to multiply the entire equation \( 2x + 7y = 14 \) by 2.
So, the equation \( 2x + 7y = 14 \) multiplied by 2 gives:
\[ 2(2x) + 2(7y) = 2(14) \]
which simplifies to:
\[ 4x + 14y = 28 \]
Thus, you should multiply by 2.