Question 1037807
Think of this order as something you will have to pay just one time, plus
something you will have to pay per pen. If x is the number of pens, then f(x) 
is the cost:
a) {{{f(x)=0.18x+27}}}
b) {{{f(x)=0.24x+15}}}
I will let you figure out part c based on the above ;-)
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Good Luck,
tutor_paul@yahoo.com