(255)/(6)*(672)/(9)+(37)/(9) how do you work this out step by step? ?

Step 1. Type it into a Google search box or calculator. (You need to use a calculator anyway.) The result is 3177 4/9.

If you're doing this according to the Order of Operations, you do the multiplication and division left to right. This means the first calculation you do is
  255/6 = 42.5
Next, you multiply by 672
  42.5*672 = 28560
Then divide by 9
  28560/9 = 3173 3/9

You continue by doing the division
  37/9 = 4 1/9

And finish by adding the two results
  3173 3/9 + 4 1/9 = 3174 4/9

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If you're doing this by hand, you can recognize the first term as the product of two fractions, so is the product of numerators divided by the product of denominators.
  (255*672)/(6*9)
Using your knowledge of divisibility rules, you can do the division 672/6 to simplify this to
  (255*112)/9
Now, the first term and the second term have the same denominator, so you can add the numerators before you do the division.
  (255*112 + 37)/9 = (28560 + 37)/9 = 28597/9
You end up having to do only two simple divisions, rather than 3 of them.
  28597/9 = 3177 4/9