Answer:
Step-by-step explanation:
The first diagram and second diagram both shows 1 + 2 + 3 + 4
The third diagram shows :
First diagram + second diagram = 4 squares row x 5 squares column
First diagram = second diagram
So, 2 times first diagram = third diagram
2 x (1+2+3+4) = 4 x 5
1+2+3+4 = [tex]\frac{4x5}{2}[/tex]
