Helen rented a kayak at the lake. There is a charge of $8 as an initial fee and then $2 an hour for every hour that she uses the kayak. If the total charge is $20, how many hours did she kayak?
If it is an $8 initial fee, then you must take $8 dollars off of the total charge of $20, leaving you with $12. $12 divided by $2 per hour is 6. Helen used the kayak for 6 hours
The number of hours she uses the Kayak is: 6 hours.
It is given that:
There is a charge of $8 as an initial fee and then $2 an hour for every hour that Helen uses the kayak.
Hence, the cost function is given by:
\(f(x)=8+2x\)
where x is the number of hours she uses the kayank.
If the total charge is: $ 20
i.e.
\(8+2x=20\\\\i.e.\\\\2x=20-8\\\\i.e.\\\\2x=12\\\\i.e.\\\\x=\dfrac{12}{2}\\\\i.e.\\\\x=6\)
Hence, the answer is: 6 hours.