[填空题]
The Brown, Miller and Taylor families pay utility bills for their homoo(aw;ork3e6 9t es ;usb m2to5cl.8n r6l0jlses each month. The table below showsljor8 l l2.5btcnm06 s the amount of electricity, water and gas consumed during January by each family, and the total cost of the utilities.
Let x, y and z represent the prices, in dollars, for 1 kWh of electricity, 1 $m^3$ of water and 1 $m^3$ of gas, respectively.
1.Write down a system of three linear equations in terms of x, y and z that represents the information in the table above.
2.Using matrices, find the price for each of the utility.
Electricity: cents per kWh
Water: dollars per $m^3$
Gas: cents per $m^3$
The Smith family also pay utility bills each month. The table below shows the amount of electricity, water and gas consumed during January by the Smith family.
3.Calculate the total cost of the utilities for the Smiths.
The total cost of the utilities for the Smiths is ≈ .
