Question

ABCD is rhombus ANGLE A-ANGLE B=30 then what is a value of angle c and D

Answer 1

If the rhombus angles have been named in the conventional way, we can assume that angle A and angle B are NOT opposite angles.
A and B must then be base angles which in a rhombus always add to 180°.
We are told
ANGLE A - ANGLE B=30
and we know that
ANGLE A + ANGLE B = 180
Adding the two equations we get
2 * Angle A = 210°
Angle A = 105°
Therefore, Angle B = 75°