To solve the equation \( \sin(3x + 10^\circ) = \cos(2x - 10^\circ) \), we can use the relationship that states that \( \sin(\theta) = \cos(90^\circ - \theta) \).
Using this property, we can rewrite the equation as:
\[ \sin(3x + 10^\circ) = \sin(90^\circ - (2x - 10^\circ)) \]
Rearranging the right side:
\[ \sin(3x + 10^\circ) = \sin(90^\circ - 2x + 10^\circ) = \sin(100^\circ - 2x) \]
Now, we have:
\[ 3x + 10^\circ = 100^\circ - 2x \]
Next, we solve for \( x \):
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Add \( 2x \) to both sides: \[ 3x + 2x + 10^\circ = 100^\circ \] \[ 5x + 10^\circ = 100^\circ \]
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Subtract \( 10^\circ \) from both sides: \[ 5x = 90^\circ \]
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Divide by 5: \[ x = 18^\circ \]
Thus, the correct value of \( x \) is \( 18^\circ \).
So the answer is \( \boxed{18^\circ} \).