This is a system of equations problem:
Part one set up general equations
1) Peanuts = 3x ($3 per pound)
2) Jellybean = 1.5y ($1.50 per pound)
Relate x and y to the information you have
He wants 30lb. total: x + y = 30
He also wants the mixture to be valued at $2.50 per pound = 3x + 1.5y = 30(2.5)
*I'm taking $2.50 times 30 because you want the total cost to equal since he wants $2.50 per pound.
You want to substitute one equation into the other.
x + y = 30
3x + 1.5y = 75
1) x + y = 30 => x = 30 - y
2) 3(30 - y) + 1.5y = 75
3) 90 - 3y + 1.5y = 75
4) -1.5y = -15
5) y = 10lb.
Then plug that into one of the original equations to get x.
6) x+ y = 30 => 10 + x = 30 => x = 20lb.
He wants 20lb. of peanuts and 10lb. of jellybeans
