10 c/min=____qt/h

Start out with this fraction

  10 c
-------
 1 min

Now we need to cancel away the "c" in the top.
We use the fact that 4 c = 1 qt, to create
a fraction which equals 1 to multiply that
by, which has "c" on the bottom to cancel 
away the "c" in the top.

Such a fraction is

 1 qt
------
 4 c

so we multiply by that:

  10 c     1 qt
------- × ------
 1 min     4 c

And then the "c"'s cancel out:

     1
  10 c     1 qt
------- × ------
 1 min     4 c
             1

Next we need to create another 
fraction that equals 1 to 
cancel away the "min" in the 
bottom of the first fraction.
We know that 60 min = 1 h, so 
we create the fraction 

 60 min
--------
  1 h

to multiply by. Notice we
put "min" in the top to
cancel away the "min" in
the bottom in the first
fraction. So now we have:

     1
  10 c     1 qt     60 min 
------- × ------ × --------
 1 min     4 c       1 h
             1


Now the "min"'s cancel out
like so

     1                  1
  10 c     1 qt     60 min 
------- × ------ × --------
 1 min     4 c       1 h
    1        1

Now all the units have canceled
except "qt" in the top and "h"
in the bottom, which are the 
units we want, so we have

 10×60 qt
----------
   4 h

Now we can cancel the 4 into the 60 and get 15

    15 
 10×60 qt
----------
   4 h
   1

So we end up with

10×15 qt
--------
   1 h

or 

150 qt/h

Edwin