Two alloys, A and B, are to be melted together to obtain 80 kg of a new alloy containing 40\% copper. Alloy A contains 25\% copper while alloy B contains 60\% copper.
(i) Form two linear equations in the masses of the two alloys A and B required.
(ii) Represent the system in matrix notation.
(iii) Solve the system to find how many kilograms of each alloy must be used.