How can you tell whether two fractions that look different represent the same number?

Ahhh !  That's where simplifying comes in.  Before you even try to
compare the fractions, make sure each one is in simplest form.

To simplify a fraction:

-- List the factors of the numerator (the top number).
   ' 1 ' is always one of them.

-- List the factors of the denominator (the bottom number).
   ' 1 ' is always one of them.

-- If there's any OTHER number (besides ' 1 ') that's a factor of both the
top and bottom, then divide the top and bottom both by that number.

-- If there's another one, then divide the top and bottom by it.

-- Keep doing that until ' 1 ' is the only factor of both the top and bottom
numbers.  Then you know that the fraction is in simplest form.

When you have simplified both fractions to their simplest form, THEN you
can compare them, and see whether they represent the same number. 
If they do, then their simplest forms will both look exactly the same !