Goldilocks need to find at least 12lb of gold and at least 18lb of silver to pay her monthly rent. There are two mines in which Goldilocks can find gold and silver. Each day that Goldilocks spends in mine 1, she finds 2lb of gold and 2lb of silver. Each day that Goldilocks spends in mine 2, she finds 1lb of gold and 3lb of silver. Formulate and LP to help Goldilocks meet her requirements while spending as little time as possible in the mines. Please clearly define the decision variables, objective function, and constraints.