As per the problem
Soda is on sale for $0.50.
and you have a coupon for $0.80 off your total purchase.
we are supposed to write a function rule for the cost of an can of soda.
If you buy x cans of soda then the cost function can be written as
[tex] C(x)=0.5x-0.80\\
\\
\text{we can replace x by the number of cans, here we have x=1 }\\
\\
C(1)=0.50*1-0.80 [/tex]
