-mnp(3m - 5n + 7p) =
-3m^2np + 5mn^2p - 7mnp^2 <==
Hello there,
I hope you and your family are staying safe and healthy during this winter season.

We need to use the Quadratic Formula*
, 
Thus, given the problem:

So now we just need to plug them in the Quadratic Formula*
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As you can see, it is a mess right now. Therefore, we need to simplify it
, 
Now that's get us to the final solution:
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It is my pleasure to help students like you! If you have additional questions, please let me know.
Take care!
~Garebear
30 centimeters cubic centimeters
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
#SPJ1
It is C: Given, Reflexive Property