The number line strategy is much more useful when we don't have something with 64 potential steps spread over a range of only 5 percentage points...
I.e. - if we had 64 percentage points - where one was 20% nuts and the other was 84% nuts, then we'd be more able to apply the number line strategy here --
As it is, we have 5 percentage points.
If we had equal amounts of P and Q, (32 oz each) then we'd have 22.5% nuts in the final mix. Since we have 15/64 of the final mix almonds, which is roughly 23%. This means we must have more of the mix that contains 25% almonds than the mix that has 20% almonds.
Here's the concept:
The higher the proportion of the 25% mix we have, the higher the proportion of almonds in the final mix, and at the extreme end, if we have 100% of Brand Q, then we have 25% almonds in the final mixture. If, on the other hand, we have 100% of Brand P, then we have 20% almonds in the final mixture. Since our final mix is about 23%, we know that this is skewed closer to 25% than to 20%, telling us we have slightly more of Brand Q than of Brand P.
Hope this helps a bit -
Apologies for the typo - we don't use pre-written answers on these, so occasionally we make a typo in our calculations. We do our best to catch these, but one slips through from time to time. Hopefully, it doesn't detract from the explanation itself or the concepts presented.