To Mix A Punch, Lindsay Begins With 3 Liters Of Lemon-lime Soda And Adds 1,893 Milliliters Of Cranberry Juice. How Many 250-mL Glasses Of Punch Can Be Served? Note: Round To The Nearest Tenth.

Well your smallest common measure here is milliliters, and you want to know number of glasses in Ml also,  so you can begin by converting all quantities to milliliters.

There are 1000 milliliters in 1 liter.

3 liters = 3000 milliliters soda
add:  1893 Ml cranberry juice

(so without the vodka ...LOL) you have 4893 milliliters of punch total.

Now divide 4893 by 250 to find out how many 250 Ml glasses of punch can be had:  4893/250= 19.572 glasses. Rounded (up) to nearest tenth is 19.6 glasses (just a little over 19 and a half glasses)

When you serve 10 Milliliters per each glass, 489 glasses are served with 10 Milliliters of Punch and a glass with 3.
When you serve 1 per each, it can be bloated to 4893.

When you try to fill 250 Milliliters into 250 Milliliter glass, some of it will spills out by the way.