First, work on the individual pieces.
The expression 4 - 4 / (x+10) requires a common denominator so that 4 / (x+10) can be subtracted from 4
Since 4 has no denominator (or, equivalently, a denominator of 1), we can simply give it the same denominator as 4 / (x+10) by multiplying it by (x+10) / (x+10)
Now we have 4 (x+10) / (x+10) - 4 / (x+10)
Since they have the same denominator, they can be combined into a single fraction rather than two fractions, turning the expression into
[4 (x+10) - 4] / (x+10)
Distributing the 4 then gives (4x + 40 - 4) / (x+10),
which becomes (4x + 36) / (x+10)
After factoring 4 out of the numerator, this becomes 4 (x+9) / (x+10)
A very similar process is then done for 8 + 8 / (x+10), after which we have
[ 4 (x+9) / (x+10) ] / [ 8 (x+11) / (x+10) ]
To divide a fraction by another fraction, we must change it into multiplication by the reciprocal of the second fraction, so this expression becomes
[ 4 (x+9) / (x+10) ] • [ (x+10) / 8 (x+11) ]
Cancelling out each (x+10) turns this into
4 (x+9) / [ 8 (x+11) ]
Since 4 / 8 can be reduced to 1 / 2, this becomes
(x+9) / 2 (x+11)
This is as simplified as it can be, so the answer is
a = 9
b = 2
c = 11
