In right triangle DBC shown below, what is the value of $$x$$?

Incorrect.
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Check your calculations.

Incorrect.
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You might have gotten this answer if you calculated $$\angle ACB$$, rather than $$x$$.

Incorrect.
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Carefully check your work.

Correct.
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It's better to look at the big triangle and add up all angles to get 180.
>$$\angle BAC + \angle ABC + \angle ACB = 180$$
>$$40+90+(20+x) = 180$$
>$$x+150 = 180$$
>$$x=30$$

Incorrect.
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Carefully check your calculations.

20°

30°

40°

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60°