6r 3r
J_______K_______L
--------------27------------
JK + KL = JL
6r + 3r = 27
9r = 27
r = 27/9
r = 3 <=====
Answer:

Step-by-step explanation:

Adding 2a to both sides

Taking sqrt on both sides

C.21
5^2-4=21
Explanation
The length of HJ is 3.5 cm
<h3>What is Congruency?</h3>
Two geometric figures are said to be congruent, or to be in the relation of congruence, if it is possible to superpose one of them on the other so that they coincide throughout.
Given:
AB = 3.5 cm, BC = 2.4 cm, and AC = 4.2 cm
As, ΔABC ≅ ΔHJK
So,
AB = HJ
BC = JK
AC = HK
Thus, HJ= AB = 3.5 cm
Learn more about this concept here:
brainly.com/question/4229988
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