Answer: 
Step-by-step explanation:
Given the equation 
you need to solve for the variable "b".
You need to apply Distributive property on both sides of the equation:
Now you need to add 21 to both sides of the equation:
Subtract 
from both sides:
And finally, you can divide both sides of the equation by 18:
Answer:
116°
Step-by-step explanation:
(there are 2 right angles)
90 + 90 = 180
180 + 64 = 244
(a quadrilateral adds up to 360°)
360 - 244 = 116
(2) + (2)
=> 8x - 6y = -46 ———(3)
(1) + (3)
=> 5x + 6y + (8x - 6y) = 20 - 46
=> 13x + (6-6)y = -26
=> 13x + 0y = -26
=> 13x = -26
=> x = -26/13
=> x = -2
=> 5(-2) + 6y = 20
=> 6y = 20 + 10
=> 6y = 30
=> y = 5
x = -2, y = 5 => C
