System of Linear Equations

A man is preparing a meal consisting of foods **A,B,C**.Each ounce of food **A** contains **2 **units of protein ,**3 **units of fat & **4 **units of carbohydrates.Each ounce of food **B** contains **3,2,1** units of protein ,fats and carbohydrates resp. And each ounce of food **C **contains **3,3,2** units of P, F and C.H resp.

If the meal must provide exactly **25 **units of **P**, **24** units of **F **and **21** units of **C.H, **thenhow many ounces of each food should be used,by taking the required units of P,F and C.H as x,y,z.

Thanks