Someone told me how to get these convert passive

An object weighs 40n in air , weighs 20n when submerged jn water and 30n submerged in a liquid of unknown density .what is the density of the liquid?

Historical vs today's presidents (compare)

Kate is 14 years old and just started taking dance classes with her friends at a local dance studio. this is her first time in a dance program, so everything is new to her. her friends convinced her to join the class since they have been enjoying it for a few months. how could the following terms her succeed in the dance class? ● secondary reinforcement ● identity vs. role confusion ● observational learning how could the following terms hinder her success in the class? ● circadian rhythm ● basal ganglia ● vestibular sense