I think you would combine like Terms
        
             
        
        
        
Answer:
96 degrees
Step-by-step explanation:
STR + STQ=180 degree
Substitute
x+x-12=180
2x-12=180
2x=192
x=96
 
        
                    
             
        
        
        
Answer:
x=3
Step-by-step explanation:
 
        
                    
             
        
        
        
Answer:
i) 28 - 30i
ii) 36 + 28i
Step-by-step explanation:
i) x = 6 + i ⇒2x = 2(6 + i) = 12 + 2i
z = 4 - 8i ⇒ 4z = 4(4 - 8i) = 16 - 32i
2x + 4z = (12 + 2i) + (16 - 32i) = 28 - 30i
ii) w = -1 + 5i and z = 4 - 8i
w × z = (-1 + 5i)(4 - 8i) = -4 + 8i + 20i - 40 ⇒collect like terms
⇒collect like terms
w × z = -4 + 28i - 40
∵ 
∴w × z = -4 + 28i - 40(-1) = -4 + 28i + 40 = 36 + 28i