First you need to know the definition of a complementary angle. That means that two angles add up to 90 degrees, or a right angle.
To find an angle complementary to a 78 degree angle, you need to subtract 78 from 90. 
90 - 78 = 12
        
                    
             
        
        
        
Answer:
 or
   or    
 
Step-by-step explanation:







 or
   or    
 
 
        
                    
             
        
        
        
Answer:
1. multiply 4x4 (which equals 16)
2. add that answer to 3 (which equals 19)
Step-by-step explanation:
Use PEMDAS (Solve in parentheses first, then exponents, multiplication, division, addition, and subtraction in that order) for the correct order of operations
 
        
                    
             
        
        
        
Answer:
36 1/4 in³
Step-by-step explanation:
v = 3 5/8 * 2 1/2 * 4
Convert to improper fractions
v = 29/8 * 5/2 * 4/1
Cancel
v = 29/2 * 5/2 * 1/1
Multiply
v = 145/4
Reduce
v = 36 1/4 in³