SOLUTION: <pre><b>please help me...thank you. A U.S. quart = 0.946 liter. If 355 mL of water weighs 12 ounces, how many ounces does 1 qt weigh?____ oz</pre>

please help me...thank you. 

A U.S. quart = 0.946 Liter. If 355 mL of water weighs 
12 ounces, how many ounces does 1 qt weigh?____ oz

We want to change oz per mL to oz per qt.  We start 
by putting 12 oz over 355 mL.

 12 oz
--------
 355 mL

We want to multiply this by a second fraction that 
will cancel away the milliLiters in the bottom of
the first fraction and bring in Liters. 

This fraction we multiply it by must equal to 1, 
since multiplying by 1 does not change the original 
value.

For a fraction to equal to 1, its numerator and 
denominator must be equal.

We know that 1000 mL = 1 Liter, so our fraction 
which equals 1 will have its numerator be one of 
these and its denominator be the other.

We will choose to put 1000 mL in the numerator so 
that the mL's will cancel with the mL in the 
denominator of the first fraction:

 12 oz
--------
 355 mL  

So we multiply that by the fraction

 1000 mL
---------
   1 L 

which equals 1 because its numerator and 
denominator are equal. So now we have this:

 12 oz      1000 mL
-------- × ---------
 355 mL       1 L 

Notice that the mL in the bottom of the first 
fraction will now cancel with the mL in the 
top of the second fraction.

Now we want to multiply by a third fraction 
which equals 1, i.e., one which has its 
numerator and denominator equal.

We are told above that 1 qt = 0.946 L, so our 
third fraction which equals 1 will have its 
numerator be one of these and its denominator 
be the other.

We will choose to put 0.946 L in the top of 
this third fraction so that the L will cancel 
with the L in the bottom of the second
fraction:

 1000 mL
--------
   1 L  

So we multiply also by the fraction

 0.946 L
---------
   1 qt 

which equals 1 because its numerator and denominator 
are equal. So now we have this:

                  1           1  
 12 oz      1000 mL     0.946 L 
-------- × --------- × ---------
 355 mL       1 L         1 qt
      1         1

Notice that the L in the bottom of the second 
fraction will now cancel with the L in the top of 
the third fraction.

Now we are ready to cancel the mL's and the L's

                  1           1 
 12 oz      1000 mL     0.946 L 
-------- × --------- × ---------
 355 mL       1 L         1 qt
      1         1

So we are left with only "oz" and numbers to 
multiply on top and a number and "qt" on the 
bottom:

 12 oz × 1000 × 0.946  
--------------------------
       355 qt

So we multiply 12×1000×0.946 on top and get

 11352 oz
----------
  355 qt

Now we divide numerator and denominator by 
355 to get 1 qt in the bottom, so we have

 31.97746479 oz
---------------- 
     1 qt

That's interpreted as about 31.977 oz per 
1 qt.

So that's the answer.

Edwin McCravy