Answer: 26
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Step-by-step explanation:
Jump to the last part of the question where it asks "how many pounds of type A coffee were used?". Since this is the goal we want to reach, let's make x the amount of type A used (in pounds).
This means that 3*x pounds of coffee were used for type B, since 3 times as much type B was used as type A. Example: if you use 2 pounds of type A, then you'll have 6 pounds of type B.
Type A costs 4.45 dollars per pound. If you use up x pounds of it then it costs a total of 4.45*x dollars. Type B costs 5.80 dollars per pound and if you use 3*x pounds, then it costs you 5.80*3x = 17.40x dollars. The total cost of both types is going to be 4.45x+17.40x = 21.85x dollars.
Set this equal to 568.10 and divide both sides by 21.85 to isolate x
21.85x = 568.10
21.85x/21.85 = 568.10/21.85
x = 26
We used 26 pounds of type A coffee