In addition to oxygen, several gasses are in air. carbon dioxide makes up 0.00039 of air. what is 0.00039 written as a percent ?

Solve with work both bert and ernie received an increase in their weekly salaries. bert's salary increased from $520 to $520. ernie's salary went from $580 to $645. find the percent of increase for each salary. what was the larger of the two percents ?

Multiply. write your answer in simplest form. 3/8 x 5/7

Solve this system of equations. 12x − 18y = 27 4x − 6y = 10