Answer: 27 13/14
To make this more simple, we can separate the fractions into two parts.
We can start off with subtracting the mixed numbers; 43 - 15 = 28
We are now left with 1/2 - 4/7
The lowest common denominator is 14
So we do 1/2 x 7 and 4/7 x 2
7/14 - 8/14 = 1/14
28 - 1/14 is changed to 28/1 - 1/14
Again we have to find a common denominator so we times 28/1 by 14
392/14 - 1/14 = 391/14
Simplified, this is 27 13/14