In this case, since angles A, B, C, and D share the same vertex, we can say that the sum of angles A, B, C, and D is equal to 360°.
Given that angle C is 75°, we can substitute this value into our equation:
A + B + 75° + D = 360°
Since angle B is adjacent to angles A and C, we can write:
A + B + B + D = 360°
Simplifying this equation, we have:
2B + A + D = 360°
Substituting the value of angle C, we have:
2B + A + 75° + D = 360°
Since angle B is adjacent to angles A and C, we can say that angle B is congruent to angle A. Hence, we can write:
2A + A + 75° + D = 360°
Combining like terms, we get:
3A + D + 75° = 360°
Next, we subtract 75° from both sides:
3A + D = 285°
Finally, we notice that angles A, B, C, and D share the same vertex, so their sum must be equal to 360°. Therefore, we can write:
A + B + C + D = 360°
Substituting in the known values, we have:
A + B + 75° + D = 360°
Rearranging the equation, we get:
A + B + D = 360° - 75°
A + B + D = 285°
Comparing this to our previous equation, we can say:
3A + D + 75° = A + B + D
2A + 75° = B
Since B is equal to A, we can write:
2A + 75° = A
Finally, subtracting A from both sides, we get:
A = -75°
However, since angles cannot be negative, this solution is not valid.
Therefore, there is no valid solution for angle A given that angle C is 75°.
The answer is: None of the above.