I don't know what posts are but i'm assuming you would subtract 21 from 17 and get 4.
The answer is B 1/6 just divide the first number by the second one<span />
(a)
we are given
the price of apple suddenly up by $0.75
Let's assume original price be 'p'
we are given
Sam bought 3 pounds of apple at the new price total is $5.88
so, new price = old price +0.75
price of 3 apples 
we are given that price is 5.88
so, we get equation as
.......Answer
(b)
Since, original price is p
so, we have to solve for p




so, original price is $1.21 per pound........Answer