K= {(2, 1), (3, 2), (4, 1), (5, 3)} is k-1 a function and why?

yes, each element in the domain has only one range value.
yes, each element in the range has only one domain value.
no, each element in the domain does not have one range value.
no, we don’t know the original function and therefore can’t make the determination.

With a continuous thought process.

(-0, -7) is your answer

Planet earth has a mass of 5.9726x10²⁴ kg.then: 5.9726x10²⁴ kg=100% of the total earth mass.if the water´s mass=5x10-4 % of the total mass, we can solve this problem by the rule of three.5.9726x10²⁴ %*10⁻⁴ %x=(5.9726x10²³ kg)(5*10⁻⁴  %) / 100 %=2.9863x10¹⁹ kganswer:   the mass of the planet´s water would be   2.9863 x 10¹⁹ kg.