2. Evaluate the following postfix expression. What is the actual numeric value of the expression? (10 分 )Postfix expression: 9 5 3 + × 10 8 2 － × －

4. Using the Backward Approach (Forward Reasoning) method of Dynamic Programming, find thelowest-cost path from S to T in the diagram below. Please explain the process of finding the path;answers that provide only the path without explanation will not receive credit. (20 分)