We have the following:
1.
let x a tulips
let y daffodils
therefore:

solving:

for x:

Therefore, the answer is 5 tulips and 10 daffodils
2.
let x a 30% silver
let y a 55% silver

solving:

for x:

Therefore, the answer is 480 pounds of 30% silver and 320 pounds of 55% silver