The associative property never works with subtraction.
For example:
2 - (7-8) <span>≠ (2-7) - 8
2-(-1)=3, but (-5)-8=-13
</span>
Answer: ∠1 = 109° ∠2 = 71°
<u>Step-by-step explanation:</u>
If the two angles form a linear pair, then their sum is 180°
∠1 + ∠2 = 180°
(5x + 9) + (3x + 11) = 180
8x + 20 = 180
8x = 160
x = 20
∠1 = 5x + 9
= 5(20) + 9
= 100 + 9
= 109
∠2 = 3x + 11
= 3(20) + 11
= 60 + 11
= 71
<u> CHECK:</u>
∠1 + ∠2 = 180°
109° + 71° = 180°
180° = 180° 
Answer: X-7
Step-by-step explanation:
I put it into Tiger Algebra Calculator and that is what I got. Great tool btw I would recommend.
Answer:
AD=AB
Step-by-step explanation:
3x-5=x+1
It's a square
You solve for x then plug it back in