Question 380937
your problem is stated as:

(1/2)a + (3/4)b - c
when a=8, b=4 and c=-2 

your given expression is (1/2)*a + (3/4)*b - c

you simply substitute the numbers for the letters.

your expression becomes (1/2)*8 + (3/4)*4 - (-2).

(1/2) * 8 = 4
(3/4) * 4 = 3

your expression becomes 4 + 3 - (-2).

simplify this by combining like terms to get 4 + 3 - (-2) = 7 - (-2).

Subtracting a negative number is equivalent to adding a positive number.

Your expression becomes 7 + 2.

Combine like terms again to get 7 + 2 = 9.

Your expression becomes 9.

That's your answer.

If you're still confused, send me an email with follow up questions as to which part confuses you.