Question

1 liter is equivalent to 1,000 milliliters how many litters are in 2,500 milliliters.

Answer 1

You can create and solve a proportion to get this answer. 
Let x be the number of litters in 2500.

1. Write out proportion.                         1/1000=x/2500
2. Cross Multiply.                                   1000x=2500
3. Divide by 1000 on each side.                     x=25