Question 250368
Okay...this is a classic "mixture" problem...they are solved pretty much the same way...through this setup...

(Amount of #1)(% of #1) + (Amount of #2)(% of #2) = (Total amount)(Final %)

In our problem, let x = amount of cornmeal, so that 320-x is the amount of soybean meal...notice how they have to add to 320...so if we plug in, we get
(320-x)(18%) + (x)(8%) = (320)(10%)
Here we can multiply both sides by 100 and eliminate the % signs...
(320-x)(18) + (x)(8) = (320)(10)   ...now multiply out and get
5760-18x + 8x = 3200      ...now combine like terms and get
-10x = -2560     ...divide by minus ten and get
x = 256 lbs cornmeal
320-x = 64 lbs soybean meal