Answer:
39 pounds of type A coffee were used.
Step-by-step explanation:
Given: Cost of type A coffee is $4.15 per pound and cost of type B coffee is $5.25 per pound. Also, blend used four times as many pounds of type B coffee as type A.
To find: How many pounds of type A coffee were used.
Let [tex]x[/tex] be the number of pounds of type A coffee and [tex]y[/tex] be the number of pounds of type B coffee.
Then, according to question,
[tex]4.15x+5.25y=980.85[/tex] and [tex]y=4x[/tex]
Substituting [tex]y=4x[/tex] in [tex]4.15x+5.25y=980.85[/tex], we get
[tex]4.15x+5.25(4x)=980.85[/tex]
⇒[tex]4.15x+21x=980.85[/tex]
⇒[tex]25.15x=980.85[/tex]
⇒[tex]x=\frac{980.85}{25.15}[/tex]
⇒[tex]x=39[/tex]
Therefore, 39 pounds of type A coffee were used.