Answers

2014-01-09T14:23:57+08:00
F(20) = 8(20) - 15
         = 145

This is quite easy.. maybe you should try the next questions. :)
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2014-01-14T09:27:41+08:00
You can subtitute the given X.

f(x)= 8x-15

the given X is 20 (subtitute)
= 8(20)-15
=160-15

= 145
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