Compute tool-life

Question

In a metal cutting operating, the following equation for tool-life was obtained for H.S.S. tool:

V T^0.13 f^0.6 t^0.3 = C.

Given that: tool-life(T) = 60 min,

Cutting speed (V) = 40 m/min,

Feed (f) 0.25 mm/rev,

Depth of cut (t) = 2.0

Compute tool-life, if speed, feed and depth of cut are together increased by 25% and also if they are increased individually by 25%.