To represent Sierra and Charlie's combined earnings for the week, we need to consider their hourly wage and the bonus Charlie received.
- Sierra earns $12 per hour for S hours, which is represented by \( 12S \).
- Charlie earns $12 per hour for C hours, which is represented by \( 12C \).
- Additionally, Charlie received a $40 bonus.
Thus, the combined earnings can be expressed as:
\[ 12S + 12C + 40 \]
Therefore, the correct response is:
12S + 12C + 40