college
posted by Jim .
If cashews cost $5.00 per pound and peanuts cost $1.50 per pound how do I write the formula to determine how many pound of cashews to mix with 30 pound of peanuts so that the mix will sell for $3.00 per pound.

Let C = weight cashews.
30(1.50) + 5.00*C = (30+C)(3.00) 
Let C be the # of pounds of cashews and 30 be the # of pounds of peanuts.
$3 times the total number of lb. equals the sum of the costs of separate purchases of peanuts and cashews.
(C + 30)* 3 = 5 C + 1.50*30 = 5C + 45
Solve for C