Answer:
B, x=40 is the right answer
Explanation:
DAC is one half of the right angle and CAB is another half. So, you know that since a right angle is 90 degrees, DAC + CAB must equal 90.
They have given you equations for both angles, so now its just a matter of rearranging and solving for x.
DAC = x
CAB = 2x - 30
DAC + CAB = 90
Using the equations above, we can come up with this final equation:
x + 2x - 30 = 90
If we add the x together:
3x - 30 = 90
If we move the 30 to the other side by adding it to 90
3x = 90 + 30
3x = 120
If we divide 120 by 3:
x= 40
Therefore, the answer is B
Hope this helped : )