Algebra long word problem ?

Question

soybean meal is 12% protein, cornmeal is 6% protein. How many pounds of each should be mixed together in order to get a 240 lb. mixture that is 8% protein?

Total soybean pounds --------?

Total Cornmeal pounds ------?

Answer 1

x=amt Soybean

y=amt Cornmeal

So:

x+y=240

because we want 240 lbs.

and

.12x+.06y=.08(240)

because we want to have a mixture with 8% protein

So the system is:

x+y=240

.12x+.06y=19.2

Solve for y:

y=240-x

Substitute:

.12x+.06(240-x)=19.2

.12x+14.4-.06x=19.2

.06x=4.8

x=80lbs Soybean

80+y=240

y=160lbs Cornmeal

Answer 2

S pounds of soy + C pounds of corn = 240 pound

S + C = 240

.12*S + .06*C = .08*240 = 19.2, or

12S + 6C = 1920, or (reducing by 1/6)

2S + C = 320

C = 240 - S

2S + (240 - S) = 320

S = 320 - 240 = 80 pounds soy meal

C = 160 pounds corn meal

Answer 3

s*0.12+c*0.6=0.8*240

s+c=240

Being

s: total soybean pounds

c: total cornmeal pounds

Then solve the system...

12s+6c=8*240

s+c=240  <--x6

12s+6c=8*240-

6s+6c=6*240

6s=2*240

s=80

c=160