AMC 10A/12A 2025 (Problem 2/2)

A box contains 10 pounds of a nut mix that is 50 percent peanuts, 20 percent cashews, and 30 percent almonds. A second nut mix containing 20 percent peanuts, 40 percent cashews, and 40 percent almonds is added to the box resulting in a new nut mix that is 40 percent peanuts. How many pounds of cashews are now in the box?
(A)  3.5\text{(A)}\;3.5(B)  4\text{(B)}\;4(C)  4.5\text{(C)}\;4.5(D)  5\text{(D)}\;5(E)  6\text{(E)}\;6