The correct option is D 3812 L
Amount of lemonade prepared by 1 group
= 512
∴ Amount of lemonade prepared by 7 groups
=7×512
Now,
7×512 = (7×5) +7×12
= 35 +7×12
= 35 +72
(Now, 7=2+2+2+1)
= 35 +22 +22 +22 +12
= 35 + 1+ 1+1+12
= 38 +12
= 3812
Hence, all similar 7 groups made 3812 L of lemonade
in total.