Josiah has a mass of 75 kg and wants to know how many helium-filled balloons it would take to fly. The density of helium is about 1 kg/m^3 less than regular air, which means a cubic meter of helium can lift about 1 kg. Fully inflated, a balloon has a diameter of 0.3 m and can be modeled as a sphere. He neglects the mass of the balloon in his calculations.
About how many balloons would it take to lift Josiah?
A. 660 Balloons
B. 1120 Balloons
C. 4750 Balloons
D. 5310 Balloons

Mrs. julien’s and mrs. castillejo’s classes are selling cookie dough for a school fundraiser. customers can buy packages of macadamia nut chip cookie dough and packages of triple chocolate cookie dough. mrs. julien’s class sold 25 packages of macadamia nut chip cookie dough and 30 packages of triple chocolate cookie dough for a total of $221.25. mrs. castillejo’s class sold 5 packages of macadamia nut chip cookie dough and 45 packages of triple chocolate cookie dough for a total of $191.25. (a) write the system of equations that model the problem. be sure to explain which equation represents which situation. (b) find the cost of each type of cookie. show your work. (c) explain which method you used to solve the system and why you chose that method.