Need help fast The proof below may or may not be correct. If the proof is incorrect, determine the first step number that is not justified and the reason it is not justified.

Scrub a dub toothbrushes are $4.00 each. there is a 10% discount, but there is also a 6% sales tax after the discount is applied. what is the new price after tax? round to the nearest penny

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)

Brainliest ! which of the coordinates are not of th vertices of the feasible region for the system of inequalities y≤4,,x≤5,x+y> 6 a(2,4) b(0,6) c(5,4) d(5,1)