Since the angles \( P-Q-S \) and \( R-Q-S \) are adjacent angles that together form a straight angle at point Q, their measures must add up to 180 degrees.
Given:
- Measure of angle \( P-Q-S \) is \( x \) degrees.
- Measure of angle \( R-Q-S \) is \( x - 60 \) degrees.
The equation that represents this relationship is:
\[ x + (x - 60) = 180 \]
Now, you can solve this equation to find the measure of angle \( P-Q-S \) (which is \( x \)).
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Combine like terms: \[ 2x - 60 = 180 \]
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Add 60 to both sides: \[ 2x = 240 \]
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Divide by 2: \[ x = 120 \]
Thus, the measure of angle \( P-Q-S \) is \( 120 \) degrees.