Remember this:
Denominator multiplies with the whole number(number on the side) The sum of that plus the numerator will give you the value for the numerator in the improper fraction. The denominator will stay the same.
Now try it on your own!
12×2+7=numerator.
1/2 is equivalent to 2/4 because,
2(1/2) = 2/4
So as you can see if you multiply the numerator(top) and the denominator(bottom) by the same number, you get an equivalent fraction! In my example you can see that I multiplied both by 2.
You do 9x27=243 then take 2x31=62 add 243+62=305 then take 305 and subtract it from 28 305-28=277
so if i did it right you should get n=277