Three varieties of coffee long dash— coffee a, coffee b, and coffee c long dash— are combined and roasted, yielding a 51-lb batch of coffee beans. twice as many pounds of coffee c, which retails for $9.95 per lb, are needed as coffee a, which sells for $15.99 per lb. coffee b retails for $13.21 per lb. how many pounds of each coffee should be used in a blend that sells for $12.82 per lb?

Let A, B and C be the number of pounds of each brand of coffee.
A+B+C=51 (weight) which is 3A+B=51 because C=2A, B=51-3A
15.99A+13.21B+19.90A=51×12.82=653.82 (cost) I’ve used C=2A
35.89A+13.21B=653.82
Substitute for B:
35.89A+13.21(51-3A)=653.82
35.89A+673.71-39.63A=653.82
3.74A=19.89, A=117/22 pounds, B=771/22 pounds, C=117/11 pounds.
Approximate weights are A: 5.32lb, B: 35.05lb, C: 10.64lb.

First write the relationship in words: "What number is 35% of 400?" 

Then write an equation to represent this relationship:  or, written another way

And then solve:


Then answer the question: "Adam has saved $140."