Answer:
Step-by-step explanation:
a + b = 140.......a = 140 - b
5.75a + 4.10b = 677.95
sub in 140 - b in for a in the other equation....and solve for b, the number of lbs of type B coffee
5.75(140 - b) + 4.10b = 677.95
805 - 5.75b + 4.10b = 677.95
-5.75b + 4.10b = 677.95 - 805
- 1.65b = - 127.05
b = -127.05 / -1.65
b = 77 <======= lbs of type B coffee used
a + b = 140
a + 77 = 140
a = 140 - 77
a = 63.........lbs of type A coffee used
check..
5.75a + 4.10b = 677.95
5.75(63) + 4.10(77) = 677.95
362.25 + 315.70 = 677.95
677.95 = 677.95 (correct)
I found both just so I could check my answer....and it checked out....
