SOLUTION:

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Question 310639:
Answer by PRMath(133) About Me  (Show Source):
You can put this solution on YOUR website!
Evaluate the variable expression when .a=-1/4, b=7/8, and c=1/8
8a + (7b -c)


Just "plug" in the info you are given, like this:

a = -1%2F4
b = 7%2F8
c = 1%2F8

8a + (7b - c) (original equation)
8%28-1%2F4%29 + (7%287%2F8%29 - 1%2F8) (see where the fractions are substituted in for the variables?)
-8%2F4%29 + %2849%2F8++++-++++1%2F8%29 (If you multiply 8 times -1%2F4 you will get -8%2F4 and... If you multiply 7 times 7%2F8 you will get 49%2F8)
-8%2F4+%2B+48%2F8 (If you subtract: 49%2F8+-+1%2F8 you get: 48%2F8)
-2+%2B+6 (Reduce the fractions: -8%2F4+=+-2 and 48%2F8+=+6)
4 (if you take -2 + 6 you will get 4)

I hope this helps you. :-)