Erica used 50 pounds of type B coffee
Let the number of pounds of type A coffee be A
Let the number of pounds of type B coffee be B
Total number of pounds = 123
A + B = 123.........................................(1)
Cost of 1 pound of type A coffee = $5.95
Cost of 1 pound of type B coffee = $4.40
Total cost = $654.35
5.95A + 4.40B = 654.35..........................(2)
Make A the subject of the formula in equation (1)
A = 123 - B........................(3)
Substitute equation (3) into equation (2)
5.95(123 - B) + 4.40B = 654.35
731.85 - 5.95B + 4.40B = 654.35
5.95B - 4.40B = 731.85 - 654.35
1.55B = 77.5
B = 77.5/1.55
B = 50
Erica used 50 pounds of type B coffee
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