Arc length formula help!

Question

find r. s = 16 cm, ? = 48°; r = ?

Answer 1

360 / 48 = 2∏r / 16 

(for 360^o, arc length is 2∏r) = (for 48^o, the arc length is 16 )

7.5 * 16 = 2∏r

r = 19.09 cm