y = - 1/2 - 4

It
looks like you are trying to collect like terms in order to solve for y. This can be tricky when
both numbers you are working with are negative. And working with fractions can be tricky, too.
So let's look at each of those separately.

You're beginning with a negative
number. In this case, it's negative 1/2. I tell students whom I tutor to think about negatives
in terms of money. So if I have a negative number, that means I'm in debt. In this case, I owe
you 1/2 (which converted to a decimal would be .50).

So I'm starting out
already "in the hole," over in the negatives. And then I go further into the negatives
by borrowing 4 more dollars from you. I was sitting at negative 1/2 and then went further
negative, so now I have a combined negative total of -4.5 or -4 1/2. (These are equal, but pay
attention to directions as sometimes teachers ask that answers be left as proper fractions and
other times you are directed to convert fractions to decimals.)

If asked to
convert to a decimal, you can again think of the fraction in terms of money. 1/2 of a dollar
(which is worth 100 cents, so it works well with thinking about fractions this way) is .50. Or
you think of it as a division problem (1 divided by 2), which will also equate to .50.

For my kinesthetic learners, it sometimes helps to learn to navigate the number line
into the negative numbers in order to determine how negatives are affected by both negative and
positive numbers. To do this, I draw huge number lines in chalk from about -20 to +20, with 0
being right in the middle. I then give my students problems like this one and let them stand on
the number line to work out the problem. For this one, I would ask a student to stand on -1/2,
making sure she understood where that is located on a number line. And then I would ask her to
subtract 4 from that negative number. She should then move to the left, ending up at -4.5. It
helps sometimes to practice working out problems like this with number lines, both big and
small, to learn how negative numbers work.