$4.$ Using Figure $3\mathrm{.}21$ in your book $($the diagram of the $4-$bit entry, $22-$by$-3-$bit memory$),$ answer the following questions:

a$.$ To read from the fourth memory location, what must the values of A$[1$:$0]$ and WE be$?(5$ points$)$

Note that memory is zero$-$indexed

b$.$ To change the number of entries in the memory from $4$ to $60,$ how many additional address lines would be needed? What would the addressability of the memory be after this change was made? Your answer must be numerical. $(5$ points$)$