Final answer:
In the context of a linear program, 20 units of slack for a constraint indicate that the constraint is not fully utilized and the solution has a buffer within the limit of that constraint. This means that additional resources can be used without affecting the feasibility of the solution.
Step-by-step explanation:
In the optimal solution to a linear program, if there are 20 units of slack for a constraint, this means that the constraint is not binding. In other words, the resources allocated to this constraint are not fully utilized; the solution is operating within the limits of the constraint, hence the term 'slack'. If a constraint has a positive slack value, the constraint does not affect the feasibility of the current solution, and the solution could still be optimized without using up all the resources or reaching the limit set by this constraint.
For example, if a constraint limits the number of burgers Alphonso can have based on his budget for burgers and bus tickets, a slack of 20 could indicate that he has the budget for 20 more burgers without exceeding his total budget.
This scenario is consistent with Alphonso's budget constraint described in the given steps, where the equation indicates the trade-off between burgers and bus tickets. The concept of 'slack' helps in understanding the buffer available within resource limits while making decisions within a budget constraint.