To find out how much money Jacqueline will earn at her two jobs this week, we can substitute the values of \( l = 5 \) (hours worked as a lab assistant) and \( s = 7 \) (hours worked as a cashier) into the equation \( 15l + 12s \).
Now let's calculate it:
\[ 15l + 12s = 15(5) + 12(7) \]
Calculating each term:
\[ 15(5) = 75 \] \[ 12(7) = 84 \]
Now, add these two results together:
\[ 75 + 84 = 159 \]
Therefore, Jacqueline will earn $159 this week.