Can someone help me solve these last 3 problems? I've been stuck on these three for the past 1.5 hours.

A camera is equipped with a lens with a focal length of 21 cm. When an object 2.3 m (230 cm) away is being photographed, how far from the film should the lens be placed? cm Need Help? Read It 13. [-/2 Points] DETAILS OBINPHYS8 9.P.011. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER A camera is equipped with a lens with a focal length of 31 cm. When an object 2.5 m (250 cm) away is being photographed, what is the magnification? Need Help? Read It 14. [-/2 Points] DETAILS OBINPHYS8 9.P.016. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER The equation connecting s, p, and f for a simple lens can be employed for spherical mirrors, too. A concave mirror with a focal length of 6 cm forms an image of a small object placed 13 cm in front of the mirror. Where will this image be located? (For spherical mirrors, positive p means the image is on the same side of the mirror as the object.) P = cm