Answer and Explanation:
The computation is shown below:
NPW of X is 
= -$20,000 - $9,000 × (P/A,12%,5) + $5,000 × (P/F,12%,5)
= -$20,000 - $9,000 × 3.604776 + $5,000 × 0.567427
= -$49,605.85
And,  
NPW of Y is 
= -$35,000 - $4,000 × (P/A,12%,5) + $7,000 × (P/F,12%,5)
= -$35,000 - $4,000 × 3.604776 + $7,000 × 0.567427
= -$45,447.11
Based on the above calculations as we can see that net present cost of Y is lower than the net present cost of X so Y should be selected