Linear programming problem

An oil fired power station burns three grades of oil: grade A, grade B and grade C.
The efficiency with which electricity can be produced from the burning of these oils
depends upon the presence of three ingredients: X, Y and Z which are known to be
present in each ton of the three grades as shown in the table below:
Tons of ingredient per ton of oil
X Y Z
Grade A 0.2 0.4 0.3
Grade B 0.1 0.3 0.2
Grade C 0.3 0.2 0.4
Maximum efficiency in the burning process requires the presence of at least 200 tons
of ingredient X, at least 175 tons of ingredient Y, and at least 300 tons of ingredient
Z, in 1 hour of continuous electricity production.
The power station purchases the oil at prices of £60, £80, and £70 per ton for grades
A, B and C respectively, and is required to operate for 12 hours per day.
Formulate the linear program which will minimize the total daily cost of
electricity production.


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Can you help us help you? What have you done on this yourself?
One sentence says "Maximum efficiency in the burning process requires the presence of at least 200 tons of ingredient X, at least 175 tons of ingredient Y, and at least 300 tons of ingredient Z, in 1 hour of continuous electricity production." What three inequalities does give you?