Step 1: Find the slope:
This gives you 
, but we need to find b.
To find b, substitute in one (x,y) pair and it doesn't matter which one. I'll go with (4,-2):
![\begin{aligned}-2&=-\dfrac{3}{2}(4)+b\\[0.5em]-2&=-6+b\\[0.5em]4&=b\end{aligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7D-2%26%3D-%5Cdfrac%7B3%7D%7B2%7D%284%29%2Bb%5C%5C%5B0.5em%5D-2%26%3D-6%2Bb%5C%5C%5B0.5em%5D4%26%3Db%5Cend%7Baligned%7D)
Now take that b-value and plug in into the slope-intercept form:
It's always a good idea to toss in the other x-value from the other point, to make sure it checks out.
-- The area of the long skinny piece on top is (6 x 33) = 198
-- The length of the dotted line between the top and bottom pieces is (33-21) = 12
-- The area of the bottom piece is (12 x 15) = 180
-- The area of the whole thing is (198 + 180) = 378
-- The perimeter of the whole thing is (33 + 6 + 21 + 15 + 12 + 15 + 6) = 108
69.75 x 0.05 = $3.49 discount
$69.75 - $3.49 = $66.26 discounted price with tax
66.26 x 0.18 = $11.93 tip
Discounted price with tax + tip
66.26 + 11.93 = 78.19
Since all the angles are congruent, the sides must be congruent too.
So, just have one equation on one side equal to another.
5x= 3x+6
Subtract 3x from both sides.
2x=6
Divide 2 into both sides.
x=3.
We can check this by seeing if all the sides are the same.
5(3)= 15
6(3)-5= 15
3(3)+6= 15
I hope this helps!
~cupcake
-6/7 < -6.7
i hope this helps
