The graph below shows the solution to a system of inequalities
which of the following inequalities is modeled by the graph?
a. x + 4y ≥ 15; y ≥ 0
b. x − 4y ≥ 15; y ≥ 0
c. x + 4y ≤ 15; y ≥ 0
d.−x − 4y ≥ 15; y ≥ 0

We have that

using a graph tool
I proceed to graph each of the cases to verify the answer
see the attached figures

the solution is the option C) x + 4y ≤ 15; y ≥ 0 

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.