How do you solve three variable systems

Could life live on earth if thare was oling oxygen in the air?

How do I solve 2/3 (4u-5)

Kurt wants to have $25,000 in an investment account four years from now. the account will pay 0.2 percent interest per month. if he saves money every month, starting one month from now, how much will he have to save each month to reach his goal

Jonahs and his aunts houses are 8,750 meters apart. Jonahs walking speed is 5 kilometers per hour. How long will it take him to walk from his house to his aunts house? Explain your thinking.

The lines y = 2x + 1 and y = - 5x - 6 intersect at?

A merry go round revolves 2 times per minute, jack is 10 feet from the center while bob is 14 feet from the center

An office uses 478 lb of paper one week. The paper comes in packages that hold 18 lb of paper each. How many packages of paper does the office use each month?

In an AP the seventh term is 38 and the twelfth term is 63. What is the sum of the first twenty terms?

Grandma has 14 red roses and 7 pink roses. How many more red roses than pink roses does she have?

What is the volume of a rectangular prism whose edges measure 3 ft, 3 ft, and 2 ft? 8 ft3 22 ft3 11 ft3 18 ft3