First, let's start with the whole number.
Half of 5 is 2.5 or 2 1/2.
4/5 translated into a decimal is 0.8, so half of that would be 0.4.
0.4 translated into a fraction is 2/5.
Add 2 1/2 to 2/5.
I'll show you the long way and the easier way.
The long way is that you find a common denominator for both fractions.
A common denominator would be 10, because you would multiply 2 and 5 (the denominators).
So this would translate the problem into 2 5/10 (Remember that whatever you do to the bottom you have to do to the top) and 4/10.
If you add these together you get 2 9/10.
The easy ways is taking the decimals in the problem (2.5 and 0.8)
Half of 0.8 is 0.4 (As mentioned above).
2.5 + 0.4.
This equals 2.9.