To properly determine mass, you could use a balancing scale and compare an object's mass to another object, whose mass is known, such as measured weights.
(To properly determine mass; could use; a balancing scale) (you; compare; an object's mass; to another object, whose mass is known, such as measured weights) (another object; is known; )
To properly determine mass you another object
could use compare is known
a balancing scale
an object's mass to another object, whose mass is known, such as measured weights