The unit meters corresponds to what variable

The atoms in a sidewalk on a hot summer day are vibrating the atoms in the sidewalk on a freezing day in winter. a. more rapidly than b. more slowly than c. at the same speed as

An object is located 30.0 cm from a concave mirror. the focal length is 15.0 c,. what is the image distance? a. 30.0 cm b. -10 cm c. 10.0 cm d. -30.0 cm

Will you chech and finish these for me, because i am stumped with them.