Amdahl's Law is as applicable to software as it is to hardware. An oft$-$cited programming truism states that a program spends $90\%$ of its time executing $10\%$ of its code. Thus, tuning a small amount of program code can often time have an enormous affect on the overall performance of a software product. Determine the overall system speedup if:

a$.90\%$ of a program is made to run $10$ times as fast $(900\%$ faster$).$

b$.80\%$ of a program is made to run $20\%$ faster.