computer architecture求大神.

computer architecture求大神.
This question requires you to generalize Amdahl’slaw to the case when multiple enhancements are possible.Three enhancementswith the following speedups are proposed for a new architecture:
Speedup1=20,Speedup2= 10,Speedup3 = 5.
Only one enhancement is usable at a time (butmultiple can be used over the entire application).If enhancements 1 and 2 areeach usable for 25% of the time,what fraction of the time must enhancement 3be used to achieve an overall speedup of 10 for the entire application?