Assuming it is referring to the blue graph (not the points), it costs more to rent adults skates.
After the first hour, it would cost 3 dollars to rent children’s skates. After the second, it would cost 6. This would make the slope 3, so the formula would be C=3h. It costs $3 per hour to rent children’s skates.
If the question is referring to the grey points, it would cost more to rent children’s skates for the first hour. After the first hour, it would cost more to rent adults skates.
The starting value (the y-intercept/the point at zero on the y axis, which is the vertical center line) is 6, and the slope is still 3 for the children’s skates.
For the first hour, it would cost $9 for children’s skates and $8 for adults skates. For two hours, it would cost $12 for the children’s skates and $16 for adults skates.
(It’s more likely that the question is referring to the blue graph)
hope this helps! if you have any questions, feel free to comment them under this answer :)