Answer:
<h2>Height (h) =54.6mm</h2>
Step-by-step explanation:
Given :
Base (b) = 7.7mm
Area (a) = 210.21mm^2
Height (h) = ?

Hey there!
840 = 100%
x = 17%
840/x = 100%/17%
(840/x) * x = (100/17) * x 840 = <span>5.8823529411765
</span>
<span>= 840/5.8823529411765 = 142.80
The correct answer to your question is option C.
The tip Christian should leave is $142.80.
Hope this helps you.
Have a great day!
</span>

Let's check I the given pairs of triangles are congruent or not ~
<h3>problem 1 </h3>

These triangles are congruent by SSS congruency, as it's three sides are equal.
・ .━━━━━━━†━━━━━━━━━.・
<h3>problem 2 </h3>

・ .━━━━━━━†━━━━━━━━━.・
These triangles are not congruent because they don't fulfill any congruency criteria.
<h3>problem 3 </h3>

These triangles are congruent by AAS congruency criteria, since two angles and one of the side is common.
・ .━━━━━━━†━━━━━━━━━.・
<h3>problem 4 </h3>

These triangles are not congruent because they don't fulfill any criteria.
・ .━━━━━━━†━━━━━━━━━.・
<h3>problem 5</h3>

These triangles are congruent by SSS congruency, as it's two sides are equal and one side is common.
・ .━━━━━━━†━━━━━━━━━.・
<h3>problem 6</h3>

These triangles are congruent by SAS congruency, since two sides and Angle between them are equal.
・ .━━━━━━━†━━━━━━━━━.・
<h3>Problem 7</h3>
These given triangles are congruent by SSS congruency, because they have two equal sides and one common side in there.
・ .━━━━━━━†━━━━━━━━━.・
<h3>problem 8 </h3>

These triangles are congruent by ASA congruency, because they have one pair equal angles, one pair of vertical opposite angles (they are equal) and a side between them equal.
・ .━━━━━━━†━━━━━━━━━.・
<h3>problem 9</h3>

These given triangles are congruent by SSS congruency, because they have two equal sides and one common side in there.
➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖