BanishingBlade gave a very thorough answer. One of the easiest ways I find to handle Dimensional Analysis at this level (see: easy peasy lemon squeezy) is to just
not think about anything. Seriously. Do not think about
shit of what anything means, just
plug in numbers. Dimensional analysis problems will give you every single piece of conversion factor you will need at this level, so frankly you just need to go through a checklist of the information they've provided
This is how i would go about thinking through this problem:
You make 6 dollars an hour. Each shift is 75 minutes. Each laundry load requires 6 quarters. How many shifts must you work to wash 10 loads?
"Okay, I wanna know how many shifts equal 10 loads of laundry. The unknown factor is shifts, the known factor is how many loads I'm doing. I'm going from # loads > # shifts"
*looks up at the problem sentences*
How many loads do I have to do?
10 loads
How many quarters does a load cost?
6 quarters
How many quarters are in a dollar?
4 quarters
How many dollars do I get paid?
6 dollars
Per what?
hour (
60 minutes)
But how many minutes are in a shift?
75 minutes
Now, write this out in a sequence of cancelling fractions
L = loads
Q = quarters
$ = dollars
M = minutes
S = shift
Code:
10L 6Q $1 60M 1S
 *  *  *  * 
1 1L 4Q $6 75M
Now then, all you do from this point is
multiply directly across and see what it gives you.
10 * 6 * 1 * 60 * 1
divided by
1 * 1 * 4 * 6 * 75
In this instance you get:
3600

1800
Now then, all you do is simplify your answer. 3600 divided by 1800? 2. What is the only conversion factor we did not cancel in that process? Shifts.
2 Shifts.