Answer:
8. HI = 25 cm
9. HJ = 27.5 cm
10. IK = 5.5 cm
Explanation:
Given segments JK=3 cm and IJ=2.5 cm of 30.5 cm length HK having points H, I, J, K in sequence, you want to find missing segment lengths.
Segment sum theorem
The segment sum theorem tells you the length of a line segment is the sum of the lengths that make it up. That means ...
HI +IJ +JK = HK
This lets you find the lengths of the various segments without concerning yourself with the value of x.
8. HI
Using the given lengths in the above sum, we have ...
HI +2.5 +3 = 30.5
HI = 30.5 -5.5 = 25
The length of HI is 25 cm.
9. HJ
The overall length is the sum of its parts:
HI +IJ = HJ
25 +2.5 = 27.5 = HJ
The length of HJ is 27.5 cm.
10. IK
The overall length is the sum of its parts:
IJ +JK = IK
2.5 +3 = 5.5 = IK
The length of IK is 5.5 cm.
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Additional comment
In case you actually want to find x, you can find it from ...
HI = 3x +4
25 = 3x +4
21 = 3x . . . . . . subtract 4
7 = x . . . . . . . divide by 3.
In this set of problems, the only use of x is to find the value of 3x+4, which you have already seen is 25.