Punch = 4/5o + 1/6c it means that any quantity of punch will have the same proportion of the two ingredients
now, you know that 1 liter can be written as 6/6 liters, so to get those 6/6 you multiply 1/6 by 6
for the proportion to remain valid, you must multiply by 6 also the other ingredient so (4/5)*6 = 24/5 of a liter of orange juice per liter of cranberry juice and 24/5 = 4.8 liters
