Answer and Explanation:
The computation is shown below;
For Alternative A 
Cost to buy new machine -$119,000.00 
 Cash received $55,000.00 
Reduction in variable manufacturing cost ($33400 - $23000) ×5 $52,000.00 
Total change in net income -$12,000.00 
For Alternative B 
Cost to buy new machine -$112,000.00 
 Cash received $55,000.00 
Reduction in variable manufacturing cost ($33400 - $10200) × 5 $116,000.00 
Total change in net income $59,000.00 
So here Xinhong should purchase a machine that belong from Alternative B.