To find out how much money Jacqueline will earn at her two jobs this week, we can evaluate the expression \(15l + 12s\) where \(l = 5\) (the number of hours worked as a lab assistant) and \(s = 7\) (the number of hours worked as a cashier).
Substituting the values into the expression:
\[ 15l + 12s = 15(5) + 12(7) \]
Calculating each term:
\[ 15(5) = 75 \] \[ 12(7) = 84 \]
Now, adding these two amounts together:
\[ 75 + 84 = 159 \]
So, Jacqueline will earn $159 at her two jobs this week.