first is solve the total volume of punch they made. but convert first the 5 L to ml.
for every 1 L there 1000 ml, 5 L ( 1000 ml / 1 L ) = 5000 ml of punch
V = 5000 ml + 750 ml
V = 5750 ml
then number of 180 ml serving
n = 5750 / 180 = 31.94 or about 31 servings of 180 ml was made.
the punch left over
v = 5750 - 180( 31) = 170 ml of the punch is left
