cutting speeds required for carbide tool Vs HSS tool

Question

Two cutting tools are being compared for a machining operation. The tool life equation are:

Carbide tool : VT¹⁶ = 3000

HSS tool : VT^0.6 = 200

Where V is the cutting speed in m/min and T is the tool life in min. the carbide tool will provide higher tool life if the cutting speed in m/min exceeds

(a) 15.0      (b) 39.4

(c) 49.3        (d) 60.0