What is the diameter of this circle if the circumference is 30pi inches

A.15 in
B.30in
C.45in
D.60in

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 anwers for 9+2x=5x-3-x

Solve each quadratic equation by factoring and using the zero product property. x^2 + 18x = 9x