Thread: percents

soy meal is 16% protein ; cornmeal is 8% protein. how many pounds of each should be mixed together to get 320-LB mixture that is 15% protein? any idea on how to solve this i hate percents -_-

Let x = amount of soy meal to be mixed. 16% of this amount is protein, or 0.16x.
Let y = amount of corn meal to be mixed. 8% of this amount is protein, or 0.08y.

The total mixture is 320 lb. The first equation represents the amounts mixed overall:


The total mixture is 15% protein, or 0.15(320) = 48. The second equation represents the amount of protein:


So here we have a system of equations:



Solve for x and y.

EDIT: Typos.

lets say i switched the numbers to 12% , 6% , 240 lbs , and 7% , i have an answer of 200 although it doesnt look correct because my y is like 12.. cant be right

This is the system that I'm getting:



If you solve this system you should get x = 40 and y = 200.