8) D
9) D
11) Twenty-five thousandths
13) A
14) Sixty-eight and 4 tenths
Not sure on 10 and 12
1.5x + 0.2y = 2.68....multiply by 0.3
1.6x + 0.3y = 2.98...multiply by - 0.2
------------------------
0.45x + 0.06y = 0.804 (result of multiplying by 0.3)
- 0.32x - 0.06y = - 0.596 (result of multiplying by - 0.2)
----------------------add
0.13x = 0.208
x = 0.208/0.13
x = 1.6
1.5x + 0.2y = 2.68
1.5(1.6) + 0.2y = 2.68
2.4 + 0.2y = 2.68
0.2y = 2.68 - 2.4
0.2y = 0.28
y = 0.28/0.2
y = 1.4
solution (they intersect at) (1.6,1.4)
The question reminds you of all the tools you need:
It says ...
"Opposite angles are equal."
So the upper right angle is x+40 just like the bottom left,
and the bottom right angle is 3x+20 just like the upper left.
And it says ...
"The sum of all angles is 360°."
You know what each of the four angles is, so you can addum all up,
set the sum equal to 360, find out what number ' x ' is, and then
use that to find the size of every angle.
