Notice that ∠BCD is opposite to ∠BAD. Since a rhombus is a parallelogram, its opposite angles are congruent. This means that their measures are equal.
m ∠BCD = m ∠BAD
We already know that m ∠BCD = 64^(∘). Substituting this into the above equation, we get that m ∠BAD= 64^(∘) as well.
Recall that in a rhombus, the diagonals bisect the angles. Therefore AC bisects ABCD. So the measure of ∠BAC is half of the measure of ∠BAD.
∠BAC=(1/2)64=32