Ram, Shyam and Mohan purchased biscuits of different brands P, Q and R.
Ram purchased 10 packets of P, 7 of Q and 3 packets of R. Shyam purchased
4 packets of P, 8 packets of Q and 10 packets of R. Mohan purchased 4 packets
of P, 7 packets of Q and 8 packets of R. If brand P costs $4, Q costs $5 and R
costs $6 each, then using matrix operation, find the amount of money spent
by these persons individually.