$(6$ points$)$ A pitfall cited in section $1\mathrm{.}11$ of the text book is expecting improve the overall performance of a computer by improving only one aspect of the computer. Consider a computer running a program that requires $250s,$ with $70$ s spent executing FP instructions, $85$ s executed Loa$\frac{d}{?}$ Store instructions, and $40$ s spent executing branch instructions, and the rest time for INT instructions.

a$)$ By how much $($percentage$)$ is the total time reduced if the time for FP operations is reduced by $20\%?$

b$)$ By how much $($percentage$)$ should the time for INT operations be reduced in order to reduce the total time by $20\%?$

c$)$ Can the total time be reduced by $20\%$ by reducing only the time for branch instructions? Why?