Calculation of tool life using taylor's tool lifeequation

Question

For tool A Taylor’s tool life exponent (n) is 0.45 and constant (K) is 90. similarly for tool B, n=0.3 and K=60. The cutting speed (in m/min) above which tool A have a higher tool life than tool B is

(a) 26.7                                   (b) 43.5

(c) 80.7                                   (d) 142.9