Me, i am single mother trying to my 10 years old boy.
jenna pays $ 66.85 for a costume pattern and 8 yard of fabric. the costume pattern cost $ 4.85. how much does each yard of the fabric cost?
thx

Jenna paid $66.85 all together, for the pattern and the fabric.

The pattern alone cost $4.85 . 
So how much did the fabric alone cost ?
Take the $4.85 away from the total:

           ($66.85) minus ($4.85)  =  $62  for fabric alone .

The fabric cost  $62  for 8 yards.
How much did each yard cost ?
One eighth ( 1/8 ) of the  $62 .
Divide the $62 by 8 to find  1/8  of it.

         ($62) ÷ (8)  =  $7.75  per yard.

Now, forgive me.  I'm probably not supposed to do this,
but I need to have a word with you.
I understand a little bit about what you're doing as a single mother ...
I raised two as a single father.  You're certainly carrying more than
one person should ever need to worry about, and when you look
back, you'll wonder how you got through it.  I wish you all the luck,
superhuman strength and endurance, and peace of mind.
We don't know each other, and the details are none of my business. 
But I do need to share with you some of what I know about math,
and I don't think you'll ever hear it said this way again.
In school math ... through high school and undergraduate college ...
the answers are NOT the important part.  The teacher does not
need to know how much Jenna paid for a yard of costume fabric,
and IF she did, she would not ask the kids in her math class ...
they're seeing it for the first time and might not calculate it
correctly.  Nobody needs the answers, and the purpose of
studying math is not to capture the answers to the problems.
The purpose of math class is to develop the mental machinery
that you use when you decide HOW to find the answer.
When somebody hands you the answer, it feels good for the
moment, because you get to fill in the blank, and maybe even
hand it in on homework.  But it's no help to the student, and it's
not fair to the student ... it snatches away the chance he had,
to exercise and build those brain muscles.
ALSO ... math builds like a brick wall.  If you don't understand
something that's covered this quarter, there's a serious chance
of running into something next quarter where you'll need it, and
you won't have this brick to stack the next one on.
What I'm saying is:  If you can possibly work it out, do your son
a big favor, and give him some time with someone who's trained
and educated to give this stuff over to a youngster.  It can be as
simple as extra time after school with his teacher, or as serious as
a math tutor in your home once or twice a week.
But get him together with somebody who's an expert in the subject,
and trained to teach it.  Maybe you won't see the difference for
another 10 years, and by then, you might not even know it when
you see it.  But he'll be better equipped to handle whatever it is
that he's handling at that time. 
The jobs are going away from working with your hands, and towards
technical and computer skills, and it's happening FAST.  Today's
elementary school kids will be doing jobs that don't even exist today.
The ones that overcame their natural fear of math and science and
maybe even learned to like those subjects will be the ones that have
the good life.

It will take him 5 days