100 liters because 4 x 100 = 400
hope this helps!!
Answer:

Step-by-step explanation:
=
We need a common denominator before we can add.
+
means the same thing as
-
= 
<span>Ok. You would set up the problem like this: 32/x=64/100 and then cross multiply; 3200=64x; divide both sides by 64; x=50. Mary has 50 customers.</span>