When you buy something on hire purchase the final price is given by:
[tex]\text{ the down payment}+\text{monthly installment}\cdot n[/tex]Where n is the number of installments. Using the data provided we have that the final purchase price is given by:
[tex]\begin{gathered} P=800+20\cdot275=800+5500 \\ P=6300 \end{gathered}[/tex]So the hire purchase price is $6300.