To solve for \( g \) in the given equations, let's start by substituting \( t = 21 - g \) into the first equation:
\[ 3t + 2g = 51 \]
Substituting for \( t \):
\[ 3(21 - g) + 2g = 51 \]
Now, distribute the \( 3 \):
\[ 63 - 3g + 2g = 51 \]
Combine the \( g \) terms:
\[ 63 - g = 51 \]
Next, isolate \( g \) by subtracting 63 from both sides:
\[ -g = 51 - 63 \] \[ -g = -12 \]
Now, multiply by -1:
\[ g = 12 \]
Thus, the solution is:
\[ g = 12 \]