Answer:
Explanation:
Let the amounts (weights) of the $1.15 mix and the $1.40 mix be c and d.
Then c + d = 30 lb. We can solve this for c, obtaining d = 30 - c.
The cost equation is ($1.15/lb)c + ($1.40/lb)d = ($1.35/lb)(30 lb)
Substituting 30 - c for d, we get:
($1.15/lb)c + ($1.40/lb)(30 - c) = ($1.35/lb)(30 lb). Solve this for c:
1.15c + 42.00 - 1.40c = 40.5.
Then -0.25c = 40.5 - 42.0, or -1.5.
Finally, -0.25c = -1.50. This yields c = 6.
If c = 6 lb, then (30 - 6) lb = d = 24 lb.
Need 24 lb of the $1.15/lb kind and 6 lb of the $1.40/lb kind.