Answer :

[tex]half a kg= \frac{1000g}{2}=500g \\\\ 500g............95p \\ 100g............x \\\\ x=\frac{100*95}{500} \\\\ x=\frac{95}{5} \\\\ \boxed{x=19p}[/tex]
1/2kg = 500g 500 x 2= 1000g costing £1.90 Divide this by ten to get 100g and your answer is 19p