Given:
We use the digit places to compute the value of a,b and c.
subtracting unit place.

If we get 1-b=6, b must be greater than 1.
We need to take one from the tenth place that is a in 9a1.
So now we get 11

If we put b=5, this equation will satisfy.

So the value of b is 5.
Subtracting tenth place values.

If we put a=10, we get

a already reduced one value.
so here a should be 11, so we take the unit digit from 11. and it takes 1 from the hundredth place is 9.
Hence the value of a is 1.
subtracting the hundredth place.
a take 1 from 9, so in this stage we have


Hence the value of c is 2.
Adding a,b, and c, we get

The answer is 8.