Peter:
£2.30 ÷ 6 = £0.38 each sausage
Paul:
£3.50 ÷ 10 = £0.35 each sausage
As you can tell, it is cheaper to buy from Paul because each sausage is £0.35 which is 3 pence less than buying from Peter.
In other words, the best value for money would go to the 10 pack sausage, saving £0.03 per unit of sausage.
However, that doesn't answer the question. You need to find how many packages you can get with your available £10.
£10 ÷ £2.30 = 4.34...
So, you can buy 4 packs of sausage from Peter - meaning you will get 24 sausages in total. This is because each pack contains 6 sausages, and you have 4 of this. (6x4=24)
£10 ÷ £3.50 = 2.85...
So, you can buy 2 packs of sausages from Paul & meaning you will get 20 sausages in toal because each package contains 10 sausages. (2x10 = 20)
Thus, you should buy from Peter because you get 24 sausages, instead of 20 sausages from Paul, in accordance to the £10 you can spend in both shops.
Hope this helps!