Question

convert the following measurements to the units specified

1) 357ml = ?L

2) 25kg = ?mg

3) 35,000cm = ?L

Answer 1

I can do this for you but that won't help. Since the concept is simple, tell me what your problem is. Here is a simple tool to help
kilo
hecta
deca
unit; i.e., grams, liter, etc
deci
centi
milli

For #1, as an example, place your pencil on milli (for mL), and move the decimal as you change from one unit to the next. Move the decimal to the left going up the scale; move the decimal to the right when going down the scale.
357 mL moves one to the left for cL, another to the left to dL and a third to the left for L. Therefore, 357 mL = 0.357 L

For 25 kg (that's kilogram), count down from kg to mg and I count 6; therefore, move the decimal to the right 6 places. That will make it
25000000 or 2.5 x 10^7 mg. Now you try the other one.

Answer 2

The third one isn't possible. You can't convert cm, a measure of length, to L, a measure of volume. Perhaps you made a typo and that is cm^3. If that is so, cm^3 is written cc (cubic centimeters) and 1 cc = 1 mL.