See the attached picture to better understand the problem
we know that
in rectangle ABCD
AB=CD
and
AD=BC
therefore
the triangle ACD and triangle ABC are congruent
so
BD=AC
BD=8 units
the answer part a) is
BD= 8 units
Part b) Find angle CBD
we know that
∠ABD+∠CBD=90°---------> by complementary angles
so
∠CBD=90-∠ABD-----> 90-67----> 23°
∠CBD=23°
the answer Part b) is
∠CBD=23 degrees
we know that
in rectangle ABCD
AB=CD
and
AD=BC
therefore
the triangle ACD and triangle ABC are congruent
so
BD=AC
BD=8 units
the answer part a) is
BD= 8 units
Part b) Find angle CBD
we know that
∠ABD+∠CBD=90°---------> by complementary angles
so
∠CBD=90-∠ABD-----> 90-67----> 23°
∠CBD=23°
the answer Part b) is
∠CBD=23 degrees