While walking ⁴/₃^th of his Normal speed ravi arrives 30 minutes early. What is normal time to cover distance.

Formula of speed :
Speed = ^Distance/_Time

Speed	s1 = 4/3 S	s2 = S
Time	t1 = t - 30	t2 = t

s₁ * t₁ = s₂ * t₂

⁴/₃S * (t - 30) = S * t

4 t - 120 = 3 t

4 t - 3 t = 120

t = 120 mintutes

By Fast Trick :

Formula of speed :

Usual Time = Numerator * Time

Putting the value in the farmula:

Usual Time = 4 * 30

Usual Time = 120

Normal time to cover the distance is 120 mintutes.