Answer:
D) 20°
Step-by-step explanation:
Using the triangle sum theorem, you know that every triangle's interior angles add up to 180°. Therefore the bottom triangle's missing angle can be found by giving it the variable x. 
57° + 30° + x = 180°
Simplify: 87° + x =180°
x=93°
By the vertical angles theorem, the vertical angle directly across this angle is congruent to this one. Meaning that the top triangle's angle are 67°, 93°, and unknown, which we can assign y. We can use the same method from above here. 
67° + 93° + y = 180°
Simplify: 160° + y = 180°
y=20°
 
        
                    
             
        
        
        
Answer: 112 in sq
Step-by-step explanation: Square: 10 x 10=100 + triangle: 10 - 6 on top = 4
4 x 16 - 10 = 6 on left so... 1/2 x 6 x 4= 12 in sq. So A= 100+12= 112in sq
 
        
             
        
        
        
12 is the answer
hope this helps!
        
             
        
        
        
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Answer:
 Cost of each hat: $5
 Cost of each mask: $3
Step-by-step explanation:
 Let be "x" the cost in dollars of a party hat and "y" the cost in dollars of a mask.
 Set up a System of equations using the information given in the exercise:
 
 You can use the Elimination Method to solve this System of equations:
 1. You can multiply the first equation by -1.
 2. Then you must add the equations.
 3. Solve for "y".
 Then:
 
 4. Now you can substitute the value of "y" into any original equation.
 5. Finally, solve for "x" in order to find its value. 
 Then:
  