1 pound is 16 ounces. And we need to keep the ratio of 7 oz almonds and 5 oz raisins.
If I multiply each quantity by the same number, the ratio should stay the same. So
7(N) + 5(N) = 16
12 N = 16
N = 16/12 = 4/3
So we need 7(4/3) = 28/3 oz of almonds = 9.33 ounces of almonds.
And we need 5(4/3) = 20/3 oz of raisins = 6.67 ounces of raisins.
Together, these make 16 oz or 1 pound. And they still have the 7 almond/5 raisin ratio.