Answer:
CD = 15
Explanation:
Pre-Solving
We are given two quadrilaterals: CDEF and GIJH.
We know that CD = 3x - 6, and GI = x + 8.
We want to find the length of CD.
Solving
Finding x
Notice how CD and GI both have one tick mark on them.
This indicates that these two are congruent, meaning that they have the same length.
Because of that, CD = GI.
If we substitute 3x - 6 for CD and x + 8 for GI, we get:
3x - 6 = x + 8
Now, we can solve this like a regular equation.
Add 6 to both sides.
3x - 6 = x + 8
+6 +6
_________________
3x = x + 14
Subtract x from both sides.
3x = x + 14
-x -x
_____________-
2x = 14
Divide both sides by 2.
2x = 14
÷2 ÷2
____________
x = 7
Finding the length of CD
We found the value of x.
Now, substitute 7 as x in 3x-6 (the length of CD).
CD = 3x - 6 = 3(7) - 6 = 21 - 6 = 15
Therefore, CD = 15.