Answer:
$13,140
Step-by-step explanation:
 MACRS-7
 Opening BV Dep. Rate Depreciation Closing BV 
Year A B C=150000*B D=A-C
1 150,000 14.29% 21,435 128,565 
2 128,565 24.49% 36,735 91,830 
3 91,830 17.49% 26,235 65,595
4 65,595 12.49% 18,735 46,860
Gain on sale = Salvage value - Book value
Gain on sale = $60,000 - $46,860
Gain on sale = $13,140