28 blue cars out of 63 cars

What is the rotational symmetry of a wheel

A33 gram sample of a substance that's used to detect explosives has a k-value of 0.1473. n = noekt no = initial mass (at time t = 0) n = mass at time t k = a positive constant that depends on the substance itself and on the units used to measure time t = time, in days

What is the value of x when x + 7 = 21?