we know that
If line WX is perpendicular to line YZ
then
see the attached figure to better understand the problem
m∠WVY=90°--------> 4a+58=90-----> 4a=90-58-----> a=32/4------> a=8°
m∠XVY=90°--------> 2b-18=90----> 2b=90+18------> b=118/2-------> b=59°
therefore
the answer is
a) The value of a is 8 degrees
b) The value of b is 59 degrees