Question 72616
First of all find f(6) by going to the original definition for f(x) and then replacing every
x by 6 and then simplifying the result.
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You were given that 
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f(x) = 7*x - 40
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Then to find f(6) you replace every x in the equation for f(x) by 6 to get:
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f(6) = 7*6 - 40
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And you simplify the right side to get:
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f(6) = 42 - 40 = 2
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So now you know that f(6) = 2
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Next you are asked to find h(f(6)) given that 
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{{{h(x) = -x^2 + 6x}}}
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To find h(f(6)) you just replace every x in h(x) with f(6). The result would be:
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{{{h(f(6)) = -(f(6))^2 + 6*(f(6))}}}
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But on the right side you can substitute for f(6) its value which we found to be +2.  If 
you do your equation becomes:
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{{{h(f(6)) = -(2)^2 + 6*2}}}
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and the right side simplifies to:
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{{{h(f(6)) = -4 + 12 = 8}}}
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So the answer to your problem is:
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{{{h(f(6)) = 8}}}
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Hope this helps you to better understand the way to work problems such as these.