Answer:
25 pounds of mix A
10 pounds of mix B
Explanation:
Each pound of mix A takes half a pound of peanuts and each pound of mix B takes one fourth of a pound of peanuts. Total peanuts consumption is:

Each pound of mix A takes half a pound of almonds and each pound of mix B takes three fourths of a pound of almonds. Total almonds consumption is:

Solving the linear system:

In order to exactly use all of your ingredients, you should make 25 pounds of mix A and 10 pounds of mix B