Answer:
78 pounds
Explanation:
Let a and b represent the numbers of pounds of the respective coffee types used. Then the following equations can be written from the problem statement:
... a + b = 132
... 5.65a + 4.15b = 628.80
We can subtract the second equation from 5.65 times the first to eliminate a.
... 5.65(a + b) - (5.65a +4.15b) = 5.65(132) - (628.80)
... 1.50b = 117.00
... b = 117.00/1.50 = 78
Aldo used 78 pounds of type B coffee in his mix.