I need help with explanation. Thanks!!

0 Ciara is a lifeguard and spots a drowning child 30 meters along the shore and 40 meters from the shore to the child. Ciara runs along the shore for a while and then jumps into the water and swims from there directly to the child. Ciara can run at a rate of 5 meters per second and swim at a rate of 0.9 meters per second. How far along the shore should Ciara run before jumping into the water in order to save the child? Round your answer to three decimal places