The most serious shortcoming of the haphazard sample selection method is:
it is not subject to statistical sampling methods.
it is time consuming to use.
it is costly to use.
it is difficult to remain completely unbiased in the selection.

Hello, your answer is: 1079, because remember, this equation represents
*800 - (-279)
so, you need to use the method of KCC, or, k=keep, c=change, c=change.
you keep the 800 positive, switch the (-) subtraction sign to a (+) addition sign, and also, make the (-279) a positive 279. so you turn out with:
*800 + 279, which equals = 1079
*youre welcome :)