Amber wants to go to a university where the tuition is $7500 per year. She has a scholarship that pays for 50% of his tuition. Her parents have given her $2000 toward her first year's tuition. How much money does Amber need to save to be able pay for first year of her college? A. $1750
B. $2200
C. $1800
D. $1550

The answer is 9.7 cm

Here is my answer, i'm sorry if you didn't understand my explanation

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.