How many monster scales are needed to create a 45 pound blend that's worth $4.50 per pound?

Question

Mrs. Gargantua got so many compliments about her tasty snack mix that she decided to sell it in stores. (If) the snack mix is made of sea monster scales, which cost $3.50 per pound, and baby whale barnacles, which are $5 per pound (How many monster scales are needed to create a 45 pound blend that's worth $4.50 per pound?)

Answer 1

Let s=weight of sea monster scales and b=weight of baby whale barnacles.

their total weight is 45lb=s+b  so b=45-s.

Cost of sea monster scales=3.5s and cost of baby whale barnacles=5b=5(45-s)=225-5s.

Cost of mixture=45×4.5=$202.50.

So 3.5s+225-5s=202.5; so 22.5=1.5s and s=15lb.

So the amount of sea monster scales is 15lb (and 30lb of baby whale barnacles).