To determine which equations have the solution \( x = 3 \), we will substitute \( x = 3 \) into each equation and check if the equation holds true.
A. \( 2x = 5 \)
Substituting \( x = 3 \):
\[ 2(3) = 5 \to 6 = 5 \] (False)
B. \( 3x = 1 \)
Substituting \( x = 3 \):
\[ 3(3) = 1 \to 9 = 1 \] (False)
C. \( 5x + 6 = 21 \)
Substituting \( x = 3 \):
\[ 5(3) + 6 = 21 \to 15 + 6 = 21 \to 21 = 21 \] (True)
D. \( 7x - 2 = 19 \)
Substituting \( x = 3 \):
\[ 7(3) - 2 = 19 \to 21 - 2 = 19 \to 19 = 19 \] (True)
The equations that have the solution of \( x = 3 \) are:
C. \( 5x + 6 = 21 \)
D. \( 7x - 2 = 19 \)
Now we need to find one more equation that fits, but from the options given, only C and D are correct. Let's conclude that only two equations have \( x = 3 \) as a solution. Only options C and D are the correct answers, and no third option is provided.