Final answer:
To ensure ZPTR is a right angle, we used the straight-line angle sum to find that y must be 25 degrees.
Step-by-step explanation:
To find the value of y so that ZPTR is a right angle, we need to use the fact that the sum of the angles in a straight line is 180 degrees. If ZPTR is a right angle, then m ZPTR = 90 degrees. Given that m ZPTQ = 3y - 10 and m ZQTR = y, the sum of these angles will be:
- m ZPTQ + m ZPTR + m ZQTR = 180 degrees
- (3y - 10) + 90 + y = 180 degrees
- 4y - 10 + 90 = 180 degrees
- 4y + 80 = 180 degrees
- 4y = 100
- y = 25
Therefore, the value of y is 25 degrees.