$(1\mathrm{.}5$ pts$)$ Compute the weakest precondition for each of the following assignment statements and

postconditions:

a$.a=2^{**}(b-1)-1\{a>3\}$

b$.b=\frac{c+10}{3}\{b<mn>6</mn><mi>\}</mi>$

c$.a=a+2**b-1\{a>5\}$

d$.$ if $x=x+1x=3^{**}x$

$\{x<mn>0</mn><mi>\}</mi>$