..Answer:
Step-by-step explanation:
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Square pyramid is the answer to your question
        
                    
             
        
        
        
Answer:
Step-by-step explanation:
In a parallelogram, the opposite sides are parallel and also equal. The opposite angles are also equal.
In parallelogram ABCD, side AD is parallel to side BC. Also, side AB is opposite and parallel to side CD. This means that AB = CD
Sides CD and AB have lengths of y + 18 and 4y, respectively. Therefore,
y + 18 = 4y
Subtracting y from the left hand side and the right hand side of the equation, it becomes
y + 18 - y = 4y - y
3y = 18
y = 18/3 = 6
Therefore, the length of AB is 
AB = 4y = 4 × 6
AB = 24