Answer:
Number 1: x = 5
Number 2: y = 3, x = 1
Number 3: x = 40
Step-by-step explanation:
For Number 1 you have to keep in mind that quadrilaterals have an interior angle measurement of 360°.
With that in mind, all the angles must add up to 360° (duh).
(20x - 16) + (81) + (16x + 10) + (15x + 30)
20x - 16 + 81 + 16x + 10 + 15x + 30 = 360
That's a bloody mess! We should really combine like terms.
20x <em>- 16 </em>+ <em>81 </em>+ 16x +<em> 10</em> + 15x + <em>30</em>
51x + 105 = 360
That looks a lot better, basic algebra from here, where we droppin' bois?
51x = 255
x = 5
--------------------------------------------------
This one's real easy.
In a parallelogram, the sides opposite from each other are equal, therefore:
2y + 2 = 4y - 4
and
x + 6 = 7x
Both are <em>very </em>easy to solve, here:
2y + 2 = 4y - 4
2y + 6 = 4y
6 = 2y
3 = y
<em>Easy!</em>
x + 6 = 7x
6 = 6x
1 = x
<em>Are you kidding me? This is easy stuff, kid.</em>
--------------------------------------------------
In a Rhombus, in case you didn't know, its diagonals (the lines connecting points diagonal to each other) are ALWAYS perpendicular to one another (intersect at 90°) which means:
2x + 10 = 90
2x = 80
x = 40
--------------------------------------------------
That will be all, ya boi Keith.
since the radius is half of the diameter we can substitute the diameter instead of using 2r. So we get 
The we can substitute the given diameter, which is 5 and multiply it by 
and get 
.