What does it mean for rows to be linearly independent?

Jessica is a custodian at oracle arena. she waxes 20 m2 of the floor in 3/5 of an hour. jessica waxes the floor at a constant rate. at this rate how many sqaures meters can she wax per hour

If the speed of an electromagnetic wave is 100,000 cm/s and its wavelength is 100 cm, what is its frequency? a) 100,000 cycles per second (hz) b) 1 × 10-3 cycles per second (hz) c) 10,000,000 cycles per second (hz) d) 1,000 cycles per second (hz)

What is r i 4.5+10r=-6.5 with work pls