Question 421152
Let x=amount of jelly beans needed
Then 30-x=amount of peanuts needed
Now we know that the total value of the peanuts and jelly beans before the mixture takes place has to equal the value of the final mixture.

Value of peanuts and jelly beans before the mixture takes place ($ understood):
1.50x+3(30-x)
Value of the final mixture:
2.10*30

So our equation to solve is:
1.50x+3(30-x)=2.10*30 simplify
1.50x+90-3x=63 subtract 90 from each side and collect like terms
-1.50x=-27
x=18 lb----------------amount of jelly beans needed
30-x=30-18=12 lb---------------amount of peanuts needed
CK
18*1.50+12*3=2.10*30
27+36=63
63=63

Hope this helps---ptaylor