The speed of sound in air is 332m/s at 0 C. At what temperature the speed become one halg of that of 0 C

Speed of sound at T^oC = Speed of sound at 0^oC + ( 0.6 x Temperature T^oC )
332/2 = 332 + ( 0.6 + T )
166 = 332 + ( 0.6 + T )
-166 = 0.6 + T
T = -166.6^oC