Question 997500
let a = number of pounds of A.
let b = number of pounds of B.
let c = number of pounds of C.


you get 3 equations that need to be solved simultaneoulsy.


they are:


a + b + c = 10 = total number of pounds.
560 a + 240b + 480c = 2000 = total number of calories.
80a + 400b + 160c = 1200 = total units of vitamins.


the calculartions are shown below:


in 1 we write the equations as shown above.


in 2 we multiply the first equation by 560 and subtract the second equation from that to get 320b + 80c = 3600


in 3 we multiply the first equation by 80 and subtract the first equation from the third equation to get 320b + 80c = 400


in 4 we subtract 320b + 80c = 400 from 320b + 80c = 3600 to get 0 + 0 = 3200


we are left with 0 = 3200 which is not true and so there is no common solution to these 3 equations.


<img src = "http://theo.x10hosting.com/2015/101904.jpg" alt="%%%" </>